What is the purpose of a crisis waiver in an annuity?

$($Search Chapter $8)$

a$.$ It waives the insurer's surrender charge for any withdrawal due to a defined circumstance or situation.

b$.$ It waives the early distribution tax penalty for a pre$-\frac{591}{2}$ withdrawal due to a defined circumstance or situation.

c$.$ It waives the payment of future premium deposits in the event of a defined circumstance or situation.

d$.$ It waives the contract's future premium payments in the event of a defined circumstance or situation.