Why is this group of words not a sentence? an apple a day

L2.4.3 test (cst): the story question 13 of 20 2 points choose the sentence that uses parallel structure correctly. o a. not only is she cutting her hair, but also coloring it. o b. he either decided to run the race or volunteer. o c. i am not only baking cookies but also brownies. od. neither my mother nor my father can watch my game.