The marriage of Isabella of Castile and Ferdinand of Aragon united

A) Spain.
B) France.
C) England.
D) Germany.
E) Italy.

Isabella of Castile

Queen of Castile from 1474 and, through marriage to Ferdinand II of Aragon, a queen of Aragon, which led to the unification of Spain under their grandson, Charles V.

Ferdinand of Aragon

Was a monarch of the late 15th and early 16th centuries, who, along with his wife Isabella of Castile, is famous for the completion of the Reconquista and the funding of Christopher Columbus's 1492 voyage.

United

Refers to entities or individuals joined together towards a common goal or forming a single entity.