Answer: The helping verbs in the sentence's verb phrase are A. should have.
Step-by-step explanation: A helping verb is a type of verb that is used together with a main verb. Generally, a helping verb is used to indicate tense; however, it can also be used to express emphasis or to add another meaning to the sentence. In that way, there are two main types of helping verbs: auxiliary verbs and modal verbs. Auxiliary verbs help expressing tense, while modal verbs might indicate a variety of meanings, such as obligation, possibility or permission. In the sentence provided, "have" is an auxiliary verb. It is used together with the main verb "gone" to indicate Present Perfect Tense. Furthermore, "should" is also part of the verb phrase, but it is a modal verb. In this case, it is expressing recommendation or advice. Despite the fact that "have" is an auxiliary verb, and "should" is a modal verb, both of them are helping verbs; therefore, the correct answer is A. should have.