Final answer:
In historical contexts, the most prominent challengers to a king's authority were The Pope, due to their power to legitimize or delegitimize a monarch's rule, and The Nobles, who had considerable influence within the kingdom's governance.
Step-by-step explanation:
The King is having a problem with who rules the kingdom, and the options are a) The Pope, b) The Queen, c) The Archbishop, d) The Nobles. Looking at historical conflicts concerning control of the kingdom, especially during the era of absolute monarchies, both the church and nobility frequently challenged royal authority. The Pope often had a significant influence on the matters of the state, as exemplified during the investiture controversy of the 11th century when Pope Gregory VII banned simony and declared Holy Roman Emperor Henry IV's rule illegitimate, sparking a rebellion against him.
The Nobles also played a crucial role in the power dynamics of kingdoms. In the feudal system, monarchs needed to share power with the noble class, and in some periods, such as during the 1789 formation of the National Assembly by commoners supported by certain clergy and nobility, the nobles had substantive power to challenge monarchical authority.
While the Queen or the Archbishop could also hold sway within the governing structure, historically, the most prominent challenges to a king's rulership would typically come from The Pope and The Nobles, with The Pope historically playing a larger role in legitimizing or delegitimizing a monarch's rule.