Final answer:
While the provided text does not reference the execution of Joan of Arc, similar historical accounts of regents include Empress Dowager Xie, Henry VIII, and Blanche of Castile, with Henry VI historically tied to Joan's fate.
Explanation:
Joan of Arc Execution:
The regent responsible for Joan of Arc's execution was not specifically mentioned in the given references, which means the answer to the student's question lies outside the provided text. Usually, historical records point towards Henry VI of England, or more precisely, officials in his name, managing the execution of Joan of Arc during her trial for heresy and witchcraft.
However, the references provided offer information about multiple regents and rulers responsible for various decisions in history. For instance, Empress Dowager Xie was involved in the situation with Jia, and King Henry VIII had Anne Boleyn executed. The regency of Blanche of Castile, who defended her son's crown, is also mentioned. Furthermore, Charles I's reign and subsequent execution led to the Interregnum under Oliver Cromwell's lordship.