Answer:
Correct answer is D. He must be a direct descendant of the previous head of government .
Step-by-step explanation:
Option D is correct answer as the the title of the king is being held by the royal Saud dynasty. King is also the prime minister of the country.
A is not correct because son is inheriting father.
B is not correct as king has great political and religious power.
C is not correct as he has the supreme power in the country.