Answer: The answer is B, should.
Explanation: A helping verb (also known as an auxiliary verb) is used with a main verb to help express the main verb's tense, mood, or voice. The main helping verbs are: "to be," "to have," and "to do." They appear in the following forms:
To Be: am, is, are, was, were, being, been, will be
To Have: has, have, had, having, will have
To Do: does, do, did, will do
There is another kind of helping verb called a modal auxiliary verb (or modal verb). The modal auxiliary verbs are "can," "could," "may," "might," "must," "ought to," "shall," "should," "will," and "would." The modal auxiliary verbs never change their forms.
