Answer:
Sample space: PP, PO, PM, PS, OP, OO, OM, OS, MP, MO, MM, MS, SP, SO, SM, SS.
Explanation:
Suppose Friend 1 select pepperoni, then Friend 2 can choose between 4 options. This gives us 4 possibilities. Then, for each selection made by Friend 1, there are 4 possibilities, given that Friend 1 has 4 different options, the sample space consists of 16 outcomes.