instruction:
This task is about writing a correct answer for the reading comprehension task. Based on the information provided in a given passage, you should identify the shortest continuous text span from the passage that serves as an answer to the given question. Avoid answers that are incorrect or provides incomplete justification for the question.
question:
Passage: The European colonization of the Americas forever changed the lives and cultures of the peoples of the continents. Although the exact pre-contact population of the Americas is unknown, scholars estimate that Native American populations diminished by between 80 and 90% within the first centuries of contact with Europeans. The leading cause was disease. The continent was ravaged by epidemics of diseases such as smallpox, measles, and cholera, which were brought from Europe by the early explorers and spread quickly into new areas even before later explorers and colonists reached them. Native Americans suffered high mortality rates due to their lack of prior exposure to these diseases. The loss of lives was exacerbated by conflict between colonists and indigenous people. Colonists also frequently perpetrated massacres on the indigenous groups and enslaved them. According to the U.S. Bureau of the Census (1894), the North American Indian Wars of the 19th century cost the lives of about 19,000 whites and 30,000 Native Americans. Question: What did the European colonization forever change?
answer:
lives and cultures of the peoples of the continents

question:
Passage: Modern electrification systems take AC energy from a power grid which is delivered to a locomotive and converted to a DC voltage to be used by traction motors. These motors may either be DC motors which directly use the DC or they may be 3-phase AC motors which require further conversion of the DC to 3-phase AC (using power electronics). Thus both systems are faced with the same task: converting and transporting high-voltage AC from the power grid to low-voltage DC in the locomotive. Where should this conversion take place and at what voltage and current (AC or DC) should the power flow to the locomotive? And how does all this relate to energy-efficiency? Both the transmission and conversion of electric energy involve losses: ohmic losses in wires and power electronics, magnetic field losses in transformers and smoothing reactors (inductors). Power conversion for a DC system takes place mainly in a railway substation where large, heavy, and more efficient hardware can be used as compared to an AC system where conversion takes place aboard the locomotive where space is limited and losses are significantly higher. Also, the energy used to blow air to cool transformers, power electronics (including rectifiers), and other conversion hardware must be accounted for. Question: What nowdays electrification systems can use?
answer:
DC motors which directly use the DC or they may be 3-phase AC motors

question:
Passage: After the assassination of Uthman in 656, Ali, a member of the Quraysh tribe and the cousin and son-in-law of Muhammad, was elected as the caliph. He soon met with resistance from several factions, owing to his relative political inexperience. Ali moved his capital from Medina to Kufa. The resulting conflict, which lasted from 656 until 661, is known as the First Fitna ("civil war"). Muawiyah I, the governor of Syria, a relative of Uthman ibn al-Affan and Marwan I, wanted the culprits arrested. Marwan I manipulated everyone and created conflict. Aisha, the wife of Muhammad, and Talhah and Al-Zubayr, two of the companions of Muhammad, went to Basra to tell Ali to arrest the culprits who murdered Uthman. Marwan I and other people who wanted conflict manipulated everyone to fight. The two sides clashed at the Battle of the Camel in 656, where Ali won a decisive victory. Question: What tribe did Ali belong to?
answer:
Quraysh