Sarah earns $40,000 per year working for a large corporation. She is thinking of quitting this job to work full time in her own business. She will invest her savings of $50,000 (which currently has an annual 10% rate of return) into the business. Her annual opportunity cost of this new business is
A) $0.
B) $40,000.
C) $45,000.
D) $90,000
Answer: $45,000.