A doctor receives $50,000 per month from her patients (and their insurance companies) as payment for her services. Each month she buys medical supplies for $10,000 and she pays a lab $15,000 for analyzing slides. The total contribution to GDP this month is:
Select one:
a. $25,000.
b. $65,000.
c. $50,000.
d. $55,000.
e. $75,000.