What is the definition of an algorithms work factor?

A.
Time it takes to encrypt and decrypt the same plaintext

B.
Time it takes to break the encryption

C.
Time it takes to implement 16 rounds of computation

D.
Time it takes to apply substitution functions

Explanation:
The work factor of a cryptosystem is the amount of time and resources
that are necessary to break the cryptosystem, or its encryption process. The goal is
to make the work factor so high that an attacker could not be successful at this
type of attack.