Final answer:
The divine right theory asserts that kings are granted the right to rule by God, establishing a divine mandate for their authority which is not subject to earthly powers or societal consent.
Step-by-step explanation:
According to the divine right theory, what gave kings the right to rule? The answer is d. God. This theory posits that monarchs are granted the authority to rule directly by a divine presence and that this right is unquestionable by any earthly force. This belief system was widely accepted in various cultures and especially in Europe after the adoption of Christianity. Monarchs were seen as God's appointed rulers over humans, much like humans rule over animals, and their authority was believed to come from their connection to the divine.
In essence, the divine right establishes that the legitimacy of a king's rule is not dependent on the consent of the governed, a constitution, the king's own strength, or any societal recognition but rather is a mandate from a higher power. Historically, this doctrine justified absolute monarchical power and meant that monarchs could govern with no need for consent from their subjects or any other entity.