An Alexa Skill Builder is developing a complex skill to help users purchase items. The Builder has implemented the default AMAZON.HelpIntent, but when users ask for help they always reach the same unhelpful result.
How should the Builder enhance the experience to guide the users toward the end goal?

A. Check the state of the user conversation when AMAZON.HelpIntent is received to give contextual responses.
B. Implement AMAZON.FallbackIntent to give a response when an utterance is not understood.
C. Extend the default AMAZON.HelpIntent with more sample utterances.
D. Implement a custom intent users can request when they need help.