Which of the following is a key purpose for political constitutions?

to arrange for orderly campaigns and elections

to set the length a president can hold office

to both define and limit the power of the government over its citizens

to make sure everyone votes on election day

C) to both define and limit the power of the government over its citizens

Explanation:

Constitutions can arrange orderly campaigns and elections and set the term lengths of presidents, however these aren't necessary to all political systems, and many constitutions can and have been created without such elements. Ensuring that everyone votes on election day is clearly ridiculous, looking at the constitution of every democracy in the world.

Therefore, it defines and limits the power of the government over its citizens. This makes logical sense based on the goal of a constitution. As a legal document describing unbreakable principles of the state it governs, it protects the citizens from government overreach, but it also protects some of the state's powers of the citizens (necessary for any nation-state in real life).