Berengaria of Portugal
Berengaria of Portugal (c. 1198 – 27 March 1221) was a Portuguese "infanta" (princess) and Queen of Denmark, by marriage to King Valdemar II.
She was the fifth daughter of King Sancho I of Portugal and Dulce of Aragon.
She was the mother of Danish kings Eric IV, Abel and Christopher I.
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.
Princess Caroline-Mathilde of Denmark
Princess Caroline- Mathilde of Denmark( 27 April 1912 – 12 December 1995) was a daughter of Prince Harald of Denmark and granddaughter of King Frederick VIII of Denmark.
As the wife of Knud, Hereditary Prince of Denmark, she became Hereditary Princess of Denmark.
Anne Denman
Anne Denman( 1587–1661) was born in Olde Hall, Retford, Nottinghamshire.
Through a fortunate second marriage with Thomas Aylesbury, she became the grandmother of Lady Anne Hyde, Duchess of York and great- grandmother of Queen Mary II and Queen Anne.
Hannah Arnold
Hannah Arnold, also known as Hannah Waterman King, was the grandmother of Benedict Arnolds children.
Hubba bint Hulail
Hubba bint Hulail was the grandmother of Hashim ibn' Abd Manaf, thus the great- great- great- grandmother of the Islamic" Nabī"( Prophet) Muhammad ibn Abdullah.
Kaoru Hatoyama
After the elections of 2009, she became more widely known as the grandmother of Prime Minister Yukio Hatoyama and his politician brother Kunio Hatoyama.
Christopher I of Denmark
Christopher I  (1219 – 29 May 1259) was King of Denmark between 1252 and 1259.
He was the son of Valdemar II of Denmark by his second wife, Berengaria of Portugal.
He succeeded his brothers Eric IV Plovpenning and Abel of Denmark on the throne.
Christopher was elected King upon the death of his older brother Abel in the summer of 1252.
He was crowned at Lund Cathedral on Christmas Day 1252.
Eric IV of Denmark
Eric IV, also known as Eric Ploughpenny or Eric Plowpenny,( – 10 August 1250) was king of Denmark from 1241 until his death in 1250.
He was the son of Valdemar II of Denmark by his wife, Berengaria of Portugal, and brother of King Abel of Denmark and King Christopher I of Denmark
Mona Hopton Bell
Mona Hopton Bell( 1867- 1940) was a British artist, best known for her portraits of civic figures.
She was the grandmother of the painter Jean H. Bell.

Question: Who is Christopher I Of Denmark's maternal grandmother?
Answer: Dulce of Aragon