Which of the following actions can make a cryptographic key more resistant to an exhaustive attack?

A.
None of the choices.

B.
Increase the length of a key.

C.
Increase the age of a key.

D.
Increase the history of a key.

Explanation:
Defenses against exhaustive attacks involve increasing the cost of the attack by increasing the
number of possibilities to be exhausted. For example, increasing the length of a password will
increase the cost of an exhaustive attack. Increasing the effective length of a cryptographic key
variable will make it more resistant to an exhaustive attack.