What is a variation of DES that uses a technique called Key Whitening?

What is a variation of DES that uses a technique called Key Whitening?
A . Blowfish
B. DESX
C. 3DES
D. AES

Answer: B

Explanation:

DESX

https://en.wikipedia.org/wiki/DES-X

In cryptography, DES-X (or DESX) is a variant on the DES (Data Encryption Standard) symmetric-key block cipher intended to increase the complexity of a brute-force attack using a technique called key whitening.