Zach has the following information to evaluate: his current salary of $$77,000$ versus total revenues of $$100,000$ and expenses of $$70,000$ from starting a new business. How much is the opportunity cost associated with staying at his current job?

A$.$ $$77,000$

B$.$ $$170,000$

C$.$ $$7,000$

D$.$ $$30,000$