Answer:
"C", C. She laughed at his joke and slapped him on the back, and walked on to class.
Step-by-step explanation:
Parallel structure means using the same pattern of words to show that two or more ideas have the same level of importance. This can happen at the word, phrase, or clause level. The usual way to join parallel structures is with the use of coordinating conjunctions such as "and" or "or."