Question: Who is Guru Hargobind's paternal grandfather?

Knowledge 1: Guru Hargobind
Guru Hargobind (19 June 1595 - 3 March 1644), revered as the "sixth Nanak", was the sixth of ten Gurus of the Sikh religion.He had become Guru at the young age of eleven, after the execution of his father, Guru Arjan, by the Mughal emperor Jahangir.Guru Hargobind introduced the process of militarization to Sikhism, likely as a response to his father's execution and to protect the Sikh community.He symbolized it by wearing two swords, representing the dual concept of miri and piri (temporal power and spiritual authority).In front of the Harmandir Sahib in Amritsar, Guru Hargobind constructed the Akal Takht ("the throne of the timeless one").The Akal Takht represents the highest seat of earthly authority of the Khalsa (the collective body of the Sikhs) today. [SEP] Knowledge 2: Guru Arjan
Guru Arjan  15 April 1563 – 30 May 1606) was the first of the two Gurus martyred in the Sikh faith and the fifth of the ten total Sikh Gurus.He compiled the first official edition of the Sikh scripture called the Adi Granth, which later expanded into the Guru Granth Sahib.He was born in Goindval, in the Punjab, the youngest son of Bhai Jetha, who later became Guru Ram Das, and Mata Bhani, the daughter of Guru Amar Das.He was the first Guru in Sikhism to be born into a Sikh family.Guru Arjan led Sikhism for a quarter of a century.He completed the construction of Darbar Sahib at Amritsar, after the fourth Sikh Guru founded the town and built a pool.Guru Arjan compiled the hymns of previous Gurus and of other saints into Adi Granth, the first edition of the Sikh scripture, and installed it in the Harimandir Sahib.Guru Arjan reorganized the Masands system initiated by Guru Ram Das, by suggesting that the Sikhs donate, if possible, one-tenth of their income, goods or service to the Sikh organization ("dasvand").The "Masand" not only collected these funds but also taught tenets of Sikhism and settled civil disputes in their region.The "dasvand" financed the building of gurdwaras and langars (shared communal kitchens).Guru Arjan was arrested under the orders of the Mughal Emperor Jahangir and asked to convert to Islam.He refused, was tortured and executed in 1606 CE.Historical records and the Sikh tradition are unclear whether Guru Arjan was executed by drowning or died during torture.His martyrdom is considered a watershed event in the history of Sikhism.It is remembered as "Shaheedi Divas of Guru Arjan" in May or June according to the Nanakshahi calendar released by the Shiromani Gurdwara Parbandhak Committee in 2003.
Knowledge 1: Guru Hargobind
Guru Hargobind (19 June 1595 - 3 March 1644), revered as the "sixth Nanak", was the sixth of ten Gurus of the Sikh religion.He had become Guru at the young age of eleven, after the execution of his father, Guru Arjan, by the Mughal emperor Jahangir.Guru Hargobind introduced the process of militarization to Sikhism, likely as a response to his father's execution and to protect the Sikh community.He symbolized it by wearing two swords, representing the dual concept of miri and piri (temporal power and spiritual authority).In front of the Harmandir Sahib in Amritsar, Guru Hargobind constructed the Akal Takht ("the throne of the timeless one").The Akal Takht represents the highest seat of earthly authority of the Khalsa (the collective body of the Sikhs) today. [SEP] Knowledge 2: Kaya Alp
Kaya Alp was, according to Ottoman tradition, the son of Kızıl Buğa and the father of Suleyman Shah, who was, in turn, the grandfather of Ertuğrul, and the great grandfather of the Ottoman Empire founder, Osman I.
Knowledge 1: Guru Hargobind
Guru Hargobind (19 June 1595 - 3 March 1644), revered as the "sixth Nanak", was the sixth of ten Gurus of the Sikh religion.He had become Guru at the young age of eleven, after the execution of his father, Guru Arjan, by the Mughal emperor Jahangir.Guru Hargobind introduced the process of militarization to Sikhism, likely as a response to his father's execution and to protect the Sikh community.He symbolized it by wearing two swords, representing the dual concept of miri and piri (temporal power and spiritual authority).In front of the Harmandir Sahib in Amritsar, Guru Hargobind constructed the Akal Takht ("the throne of the timeless one").The Akal Takht represents the highest seat of earthly authority of the Khalsa (the collective body of the Sikhs) today. [SEP] Knowledge 2: Lyon Cohen
Lyon Cohen( 1868–1937) was a Polish- born Canadian businessman and a philanthropist.He was the grandfather of singer/ poet Leonard Cohen.

Answer: Guru Ram Das