Which one of the following items may be added to a password stored in MD5 to make it more
secure?

A.
Ciphertext

B.
Salt

C.
Cryptotext

D.
Rainbow table

Explanation:
Making an Md5 Hash More Secure
To make the md5 hash more secure we need to add what is called “salt”. Salt in this sense of the
meaning is random data appended to the password to make the hash more complicated and
difficult to reverse engineer. Without knowing what the salt is, rainbow table attacks are mostly
useless.
http://www.marksanborn.net/php/creating-a-secure-md5-hash-for-storing-passwordsin-a-database/