[Math] Suppose that in a group of 5 people, there are not necessarily three mutual friends or mutual enemies.

Question

Question:
Show that in a group of 5 people (where any two people are either friends or enemies), there are not necessarily three mutual friends or three mutual enemies.

After thinking for hours I think it could be related to graph but I have no idea how start this question. May I get some assistance?

Edited: I changed the word from suppose to show

Answer 1

This picture describes everything!