Final answer:
The three parts of Parliament are the Sovereign, the House of Commons, and the Senate, making option D the correct answer.
Step-by-step explanation:
The three parts of Parliament are the Sovereign (often a monarch such as the Queen), the House of Commons, and the Senate. The correct answer to the student's question is D. The Sovereign, the House of Commons, and the Senate. The Parliament functions as the legislative body, where the House of Commons is composed of elected members called Members of Parliament (MPs), and the Senate is typically composed of members appointed on the advice of the Prime Minister. The Sovereign, while being the head of state, has a mostly ceremonial role and grants royal assent to laws passed by both houses of Parliament.