MATLAB: How do I create a program that randomly generates a string/word?

for my homework assignment, I am suppose to create a program that will play rock-paper-scissors with the user. The user will input either rock paper or scissors, and the program is to randomly choose whether to be rock, paper, or scissors. I understand how to generate the user's input, but I need help creating a program that will randomly choose a specific string at random. Any tips?