There are 7 quarters, 2 dimes, 5 nickels, and 11 pennies to choose from. What is the sample space?

The sample space is all the possible outcomes from a trial/trials;

In this case, it is all the possible coins that you can pick from;

If you are picking multiple coins, how many of each and in what order you pick them also contribute to the sample space, i. e. they produce other possible outcomes:

7 quarters, 2 dimes, 5 nickels or 11 pennies.