What determines the strength of a secret key within a symmetric key cryptosystem?

A.
A combination of key length, degree of permutation, and the complexity of the data-encryption
algorithm that uses the key

B.
A combination of key length, initial input vectors, and the complexity of the data-encryption
algorithm that uses the key

C.
A combination of key length and the complexity of the data-encryption algorithm that uses the
key

D.
Initial input vectors and the complexity of the data-encryption algorithm that uses the key

Explanation:
The strength of a secret key within a symmetric key cryptosystem is determined by
a combination of key length, initial input vectors, and the complexity of the data-encryption
algorithm that uses the key.