What three classes along with the Messaging.InboundEmailHandler are used to handle inbound email messages in Salesforce? 

Answer options:

A. Apex code, Visualforce pages, and controllers
B. Messaging.InboundEmail, Messaging.InboundEmailResult, Messaging.InboundEnvelope
C. Messaging.InboundEmailHandler
D. Make calls to methods using both valid and invalid inputs.

B