Final answer:
The sentence that contains a helping verb is 'Janice will be taking dancing lessons for the last time.'
Step-by-step explanation:
The sentence that contains a helping verb is Option B: Janice will be taking dancing lessons for the last time.
A helping verb, also known as an auxiliary verb, is used to help the main verb express tense, mood, voice, and other aspects. In this sentence, the helping verb 'will be' is used to indicate future tense and help the main verb 'taking' express the action.
Learn more about Helping verbs