As a savvy investor your course of action would be D. Both b and c.
What should the investor do ?
A CDS is a contract that pays you a certain amount if the issuer (the bank) defaults on its debt. In this case, if the bank fails, the CDS would pay you, offsetting some of your losses.
Purchasing some, or all, of the bank stocks could be a good opportunity if you believe the bank failures are temporary and the banks will recover. However, this is a risky strategy as bank stocks can be volatile, especially during financial crises.