Which of the following algorithms is a stream cipher?

A.
RC2

B.
RC4

C.
RC5

D.
RC6

Explanation:
RC4 is one of the most commonly implemented stream ciphers.
Incorrect Answers:
A, C, & D: RC2, RC5and RC6 are block ciphers.

Harris, Shon, All In One CISSP Exam Guide, 6th Edition, McGraw-Hill, 2013, p. 810
https://en.wikipedia.org/wiki/RC2