Question: Who is Robert, Archduke Of Austria-Este's maternal grandfather?

Knowledge 1: Robert, Archduke of Austria-Este
Archduke Robert, Archduke of Austria-Este (8 February 1915 – 7 February 1996), was the second son of Karl I, (beatified)last Emperor of Austria-Hungary, and Princess Zita of Bourbon-Parma. [SEP] Knowledge 2: Zita of Bourbon-Parma
Zita of Bourbon-Parma ("Zita Maria delle Grazie Adelgonda Micaela Raffaela Gabriella Giuseppina Antonia Luisa Agnese"; 9 May 1892 – 14 March 1989) was the wife of Charles, the last monarch of Austria-Hungary.As such, she was the last Empress of Austria and Queen of Hungary, in addition to other titles.Born as the seventeenth child of the dispossessed Robert I, Duke of Parma, and his second wife, Infanta Maria Antonia of Portugal, Zita married the then Archduke Charles of Austria in 1911.Charles became heir presumptive to the Emperor Franz JosephI of Austria in 1914 after the assassination of his uncle Archduke Franz Ferdinand of Austria, and acceded to the throne in 1916 after the old emperor's death.After the end of World War I in 1918, the Habsburgs were deposed and the empire became four independent countries, Austria, Hungary, and the newly formed Czechoslovakia and State of Slovenes, Croats and Serbs.Charles and Zita left for exile in Switzerland and were subsequently removed from Hungary by the Allies to Madeira, where Charles died in 1922.After her husband's death, Zita and her son Otto served as symbols of unity for the exiled dynasty.A devout Catholic, she raised a large family after being widowed at the age of 29, and never remarried.
Knowledge 1: Robert, Archduke of Austria-Este
Archduke Robert, Archduke of Austria-Este (8 February 1915 – 7 February 1996), was the second son of Karl I, (beatified)last Emperor of Austria-Hungary, and Princess Zita of Bourbon-Parma. [SEP] Knowledge 2: Maria Theresa of Austria-Este (1849–1919)
Maria Theresa of Austria-Este (Maria Theresa Henriette Dorothee; 2 July 1849 – 3 February 1919) was the last Queen of Bavaria.She was the daughter and only child of Archduke Ferdinand of Austria-Este and his wife, Archduchess Elisabeth of Austria.
Knowledge 1: Zita of Bourbon-Parma
Zita of Bourbon-Parma ("Zita Maria delle Grazie Adelgonda Micaela Raffaela Gabriella Giuseppina Antonia Luisa Agnese"; 9 May 1892 – 14 March 1989) was the wife of Charles, the last monarch of Austria-Hungary.As such, she was the last Empress of Austria and Queen of Hungary, in addition to other titles.Born as the seventeenth child of the dispossessed Robert I, Duke of Parma, and his second wife, Infanta Maria Antonia of Portugal, Zita married the then Archduke Charles of Austria in 1911.Charles became heir presumptive to the Emperor Franz JosephI of Austria in 1914 after the assassination of his uncle Archduke Franz Ferdinand of Austria, and acceded to the throne in 1916 after the old emperor's death.After the end of World War I in 1918, the Habsburgs were deposed and the empire became four independent countries, Austria, Hungary, and the newly formed Czechoslovakia and State of Slovenes, Croats and Serbs.Charles and Zita left for exile in Switzerland and were subsequently removed from Hungary by the Allies to Madeira, where Charles died in 1922.After her husband's death, Zita and her son Otto served as symbols of unity for the exiled dynasty.A devout Catholic, she raised a large family after being widowed at the age of 29, and never remarried. [SEP] Knowledge 2: Maria Theresa of Austria-Este (1849–1919)
Maria Theresa of Austria-Este (Maria Theresa Henriette Dorothee; 2 July 1849 – 3 February 1919) was the last Queen of Bavaria.She was the daughter and only child of Archduke Ferdinand of Austria-Este and his wife, Archduchess Elisabeth of Austria.

Answer: Robert I