The meet$-$in$-$the$-$middle attack demonstrates that $\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_.$

Question $6$ options:

A$)$

double encryption does not greatly diminish vulnerability to brute$-$force attack.

B$)$

Alice and Bob can kill an attacker Oscar if they coordinate.

C$)$

an attacker recognizes if the same message has been sent twice simply by looking at the ciphertext.

D$)$

faster encryption and decryption.