Answer:
D) whereby voters are given the chance to approve or disapprove some legislative act or constitutional amendment.
Explanation:
A Referendum asks citizens their opinion on a specific issue, and they usually are given two options to vote, a "yes" or a "no" most of the time. For example, three years ago the United Kingdom held a referendum on whether it should leave or remain in the European union. The leave option won, and this started a complicated process known as "Brexit".
Referendums are a form of direct democracy and were common in ancient Athens. Nowadays, a country in which they are prevalent is Switzerland, where several referendums are held each year, on a wide array of issues, from land policy, tax reform or immigration.