Given the Following Marginal Cost Estimates Associated with Obtaining Additional

Given the following marginal cost estimates associated with obtaining additional interest-checking account funding: Market interest rate 0.3%,
Servicing costs: 2.6% of balances
Acquisition costs: 0.2% of balances
Deposit insurance costs = 0.25% of balances
Net investable balance = 85% (10% required reserves and 5% float)
What is the estimated marginal cost of obtaining additional interest-checking balances?

A) 2.85%
B) 3.35%
C) 3.53%
D) 3.72%
E) 3.94%