Question: Which is a principle of political democracy that underpins universal suffrage and political equality?

Context paragraphs:
Traditionalism (Spain): Traditionalism (Spanish: "tradicionalismo" ) is a Spanish political doctrine, formulated in the early 19th century and developed until today.  It understands politics as implementing the social reign of Jesus Christ.  In practical terms it advocates a loosely organized monarchy combined with strong royal powers, with some checks and balances provided by organicist representation, and with society structured on a corporative basis.  Traditionalism is an ultra-reactionary doctrine; it rejects concepts such as democracy, human rights, constitution, universal suffrage, sovereignty of the people, division of powers, religious liberty, freedom of speech, equality of individuals, parliamentarism and so on.  The doctrine was adopted as theoretical platform by a socio-political movement named Carlism, though it appeared also in a non-Carlist incarnation.  Traditionalism has never exercised major influence among the Spanish governmental strata, yet periodically it was capable of mass mobilization and at times partially filtered into the ruling practice.

Tell me (advertisement): Tell me is the title of an advertisement calling for universal suffrage in Hong Kong.  It ran once as a full page ad on the front page of most Hong Kong newspapers on 28 October 2005, and inspired many other people and groups in Hong Kong to run advertisements supporting democracy, in response to the government's reform proposal which ruled out universal suffrage in 2007 and 2008 elections.

Ulrike Guérot: Ulrike Beate Guérot (born 1964 in Grevenbroich) is a Berlin-based German political thinker and Founder and Director of the European Democracy Lab (EDL), a think tank dedicated to the future of European democracy.  The „Mission Statement“ of the European Democracy Lab is the realization of a political entity in Europe based on the general principle of political equality and the development of a European parliamentarism that corresponds to the idea of division of power.  In April 2016, Danube University Krems appointed Ulrike Guérot as Professor for European Policy and the Study of Democracy.  She is the head of the Department for European Policy and the Study of Democracy.

Uddevalla Suffrage Association: The Uddevalla Suffrage Association (Swedish: "Uddevalla Rösträttsförening" ) was a late-19th-century political movement founded in Uddevalla, Sweden.  Local historians and the Swedish Social Democratic Party consider it the first political predecessor of the Swedish labour movement in the province of Bohuslän.  Its purpose was to bring about universal suffrage in Sweden: At the time, suffrage in the country was restricted to men and based on personal wealth, therefore excluding most of the urban and rural working class from the electoral process.  The Uddevalla Suffrage Association was one of many groups throughout Sweden that helped bring democratic thought into the common discourse and make way for the political breakthrough of the labour movement.

Sarah Massey Overton: Sarah Massey Overton (1850-1914) was a suffragist, women's rights activist, and African-American rights activist.  She was born in Massachusetts but moved to California in the 1880s.  There she attended St. Phillip’s Mission School.  In 1869 she married, and then she ran a catering business with her husband.  In the 1880s she became a leader in the fight to allow African-American children in California to attend public school.  In 1906 she cofounded San Jose’s Garden City Women’s Club, and as a member of it she lobbied in favor of interracial women’s club coalitions for women's suffrage.  She lobbied for women's suffrage in the 1911 statewide election in California, and was vice-president of San Jose’s interracial Suffrage Amendment League.  She also did voter registration of men in California who supported women's suffrage, doing this through the Political Equality Club of San Jose.  She was also president of the all-black Victoria Earle Matthews (Mothers) Club, which helped girls and women who had been sexually abused or threatened with such.  She had a daughter named Harriet and a son named Charles.

Reserved political positions: Several politico-constitutional arrangements use reserved political positions, especially when endeavoring to ensure the rights of minorities or preserving a political balance of power.  These arrangements can distort the democratic principle of "one person - one vote" in order to address special circumstances.

One man, one vote: One man, one vote (or one person, one vote) is a principle of political democracy that underpins universal suffrage and political equality.  During the 20th-century period of decolonisation and the struggles for national sovereignty, from the late 1940s onwards this phrase became widely used in developing countries where majority populations sought to gain political power in proportion to their numbers.

Universal suffrage: The concept of universal suffrage, also known as general suffrage or common suffrage, consists of the right to vote of all adults, subject only to minor exceptions.  Many countries make an exception for small numbers of adults that are considered mentally incapable of voting.  Other countries also exclude people convicted of serious crimes or people in jail, but this is considered a violation of a basic human right in an increasing number of countries.  In some countries, including the United States, it is very difficult and expensive for convicted criminals to regain this right even after having served their jail sentence, but U.S voting laws are not national, but subject to federalism so some states have more lenient voting laws.  In any case, where universal suffrage exists, the right to vote is not restricted by race, sex, belief, wealth, or social status.

Nepalese Rastriya Panchayat election, 1981: Elections were held to the Rastriya Panchayat (National Parliament) in Nepal on 9 May 1981.  80% of the seats were elected through adult universal suffrage; this was the first election through universal suffrage held in Nepal in 22 years.  However, political parties were banned at the time, and the main underground opposition forces (the Nepali Congress and various communist groups) called for a boycott of the election.

Pieter Rink: Pieter Rink was a successful lawyer in Tiel.  He was a member of the Liberal Union "(Liberale Unie)" and served in the city council of his city of birth (1883–1905) and was a member of the States-Provincial of Gelderland (1903–1905).  In 1891 he was elected in the House of Representatives (Dutch lower house of parliament) and remained a member till 1922 (except in the period 1905-1908 when he was Minister of the Interior).  From July 1918 till April 1921 he was the president of the parliamentary group of the Liberal Union and from April 1921 till July 1922 he served as the first president of the Freedom League parliamentary party.  In 1923 he was elected to the Senate (upper house), remaining a member till 1933.  In the years prior to the introduction of universal suffrage (introduced in 1917) he was an ardent advocate of suffrage extension and was considered a ""Takkiaan"".  This fact was underlined in the party brochure he co-authored, "Het kiesrechtvraagstuk" ("The Suffrage Question") which was published in 1903 and called for the introduction of universal suffrage, female suffrage and a reform of the electoral system.

Supporting paragraphs: Reserved political positions One man, one vote
Answer: One man, one vote (or one person, one vote) is a principle of political democracy that underpins universal suffrage and political equality.