How could Marketing Cloud Connect be used to initiate these sends when contacts for select accounts are created?

A B2B customer has customized journeys they want to use for several key accounts they are trying to sell into.

How could Marketing Cloud Connect be used to initiate these sends when contacts for select accounts are created?
A . Salesforce Campaign Entry Source on the Lead Object
B. Salesforce Data Entry Source on the Contact Object
C. Salesforce Data Entry Source on the Account Object
D. Welcome Email Configuration on the Account Object

Answer: C