Which institution comprises the House of Commons, the House of Lords, and the monarch in the UK?

The correct choice is Parliament because it is the legislative body of the United Kingdom, which is made up of three key components: the House of Commons, the House of Lords, and the monarch. Parliament is responsible for making and passing laws, scrutinizing the government, and representing the electorate. The two houses play distinct roles; the House of Commons is made up of elected Members of Parliament (MPs) who represent the people, while the House of Lords consists of appointed and hereditary members who provide expertise and review legislation. The monarch's role, although largely ceremonial today, includes the formal approval of legislation known as Royal Assent.

The Cabinet, while an important part of the government, is comprised of senior ministers chosen from the majority party in the House of Commons and is responsible for the day-to-day governance of the country, rather than being an institution that includes the monarch and both houses. The Supreme Court is the highest court in the UK and deals with legal matters and interpretations of law, but it does not have legislative functions. The Council of Europe is an international organization focused on promoting human rights and democracy across Europe, but it is separate from the UK’s parliamentary system.