Answer:
d) Ann is the principal and Mary is the agent.
Explanation:
In the given condition, Ann is unable to do negotiate so she hires Mary who works for Ann.
Ann is the principal as she is interested to purchase Ted's factory which represents the main role of the agreement. Without Ann, the agreement would not be completed whereas Mary is the agent as she does the negotiations on behalf of Ann.
Hence, option d is correct
Since Mary is hired to do the negotiations, the answer D.) is correct.