Question: Who is Prince Christian-Sigismund Of Prussia's maternal grandmother?

Knowledge 1: Prince Christian-Sigismund of Prussia
Prince Christian-Sigismund of Prussia (born March 14, 1946) is one of the three paternal uncles of Georg Friedrich, Prince of Prussia, head of the House of Hohenzollern since 1994, which reigned over Germany until 1918.He is the youngest of four sons born to Louis Ferdinand, Prince of Prussia (1907-1994) and Grand Duchess Kira Kirillovna of Russia (1909-1967).He was the heir presumptive to the headship of the deposed House of Hohenzollern from the death of his father to 20 January 2013, when Georg Friedrich fathered twin sons, relegating Christian-Sigismund to a more remote place in the Line of succession to the former German throne. [SEP] Knowledge 2: Grand Duchess Kira Kirillovna of Russia
Grand Duchess Kira Kirillovna of Russia (9 May 1909 – 8 September 1967) was the second daughter of Grand Duke Kirill Vladimirovich of Russia and Princess Victoria Melita of Saxe-Coburg and Gotha.She married the head of the German Imperial House, Prince Louis Ferdinand of Prussia.
Knowledge 1: Prince Christian-Sigismund of Prussia
Prince Christian-Sigismund of Prussia (born March 14, 1946) is one of the three paternal uncles of Georg Friedrich, Prince of Prussia, head of the House of Hohenzollern since 1994, which reigned over Germany until 1918.He is the youngest of four sons born to Louis Ferdinand, Prince of Prussia (1907-1994) and Grand Duchess Kira Kirillovna of Russia (1909-1967).He was the heir presumptive to the headship of the deposed House of Hohenzollern from the death of his father to 20 January 2013, when Georg Friedrich fathered twin sons, relegating Christian-Sigismund to a more remote place in the Line of succession to the former German throne. [SEP] Knowledge 2: Princess Barbara of Prussia
Princess Barbara of Prussia (2 August 192031 May 1994) was the only daughter and elder child of Prince Sigismund of Prussia and Princess Charlotte of Saxe-Altenburg.She was a great-granddaughter of Frederick III, German Emperor and a great-great-granddaughter of Queen Victoria.On 17 September 1952 she was legally adopted by her paternal grandmother, Princess Irene of Prussia ("née" Princess Irene of Hesse and by Rhine), a granddaughter of Queen Victoria.
Knowledge 1: Prince Christian-Sigismund of Prussia
Prince Christian-Sigismund of Prussia (born March 14, 1946) is one of the three paternal uncles of Georg Friedrich, Prince of Prussia, head of the House of Hohenzollern since 1994, which reigned over Germany until 1918.He is the youngest of four sons born to Louis Ferdinand, Prince of Prussia (1907-1994) and Grand Duchess Kira Kirillovna of Russia (1909-1967).He was the heir presumptive to the headship of the deposed House of Hohenzollern from the death of his father to 20 January 2013, when Georg Friedrich fathered twin sons, relegating Christian-Sigismund to a more remote place in the Line of succession to the former German throne. [SEP] Knowledge 2: Tjuyu
Tjuyu( sometimes transliterated as Thuya or Thuyu) was an Egyptian noblewoman and the mother of queen Tiye, and the wife of Yuya.She is the grandmother of Akhenaten, and great grandmother of Tutankhamun.

Answer: Princess Victoria Melita of Saxe-Coburg and Gotha