Question

Which words contain an affix? Check all that apply.

Answer 1

THe answer to your question is Unhappy, reread, restless, comfortable. An affix is an additional word or element attached to a word. For example Un-Happy. You are putting "un" in front of the word happy, making it unhappy

Answer 2

The words that contain an affix are:
unhappy (un-)
reread (re-)
restless (-less)
comfortable (-able)