How should a data architect model the relationship between the contact and conference objects?

Each contact may attend multiple conferences and each conference may be related to multiple contacts.

How should a data architect model the relationship between the contact and conference objects?
A . Implement a Contact Conference junction object with master detail relationship to both contact and conference__c.
B . Create a master detail relationship field on the Contact object.
C . Create a master detail relationship field on the Conference object.
D . Create a lookup relationship field on contact object.

Answer: A