You are evaluating a symmetric encryption algorithm that supports highly variable key lengths and determined that it would take an attacker three years on average to crack an $80-$bit key. If you wanted an average cracking time of $12$ years, what is the minimum key length? Choose the best response.

a$.$

$160$ bits

b$.$

$82$ bits

c$.$

$128$ bits

d$.$

$320$ bits