This term refers to a situation in a country in which all people who are citizens have the right to vote?

universal suffrage is where all citizens can vote.

Universal Suffrage

Explanation:

Universal Suffrage means that all the adult persons have been given the right to vote irrespective of their income, wealth, race gender, social status. Earlier in 19th century Britain Universal suffrage meant the right to vote for all men, it didn't included women.  In the first democracies the right to vote was restricted to the people with wealth and property. In many jurisdictions other restrictions also existed. In nineteenth century North America, great Britain and Europe witnesses the movement which demanded for universal male suffrage.

taking a bath requires the most water out of the given options because it takes a significant amount of water in order to fill a bathtub.