Answer :
The answer would be 'separate compound elements' (ex: noun + noun, noun + verb, etc.). You do not need a comma to separate these words.
separate compound elements
Compound elements are supposed to go together; that's why they are called compound. Sometimes hyphens are used to show how together compound elements are. They should not be separated with a comma. Examples of why the other three options are: In the other room, I can hear the children. He said, "I love waffles." Tomorrow, I will mow the lawn. Yes, I can go to the store.