Which of the following explains why there is a negative correlation between campaign fundraising and electoral success for incumbents?

a. FEC rules require this pattern of fundraising and spending.
b. Challengers tend to have less name recognition, meaning their early spending is more cost-effective.
c. Vulnerable incumbents tend to ramp up fundraising, while safe incumbents need not spend as much time fundraising.
d. Incumbents hope to scare off high-quality opponents by overspending.

c. Vulnerable incumbents tend to ramp up fundraising, while safe incumbents need not spend as much time fundraising.