Why Are Diamonds Sometimes Used to Represent Relationships in an REA

Why are diamonds sometimes used to represent relationships in an REA diagram?

A) Because there is only one way to draw REA diagrams and that requires diamonds.
B) Because diamonds provide a place to label the relationships.
C) There is no reason to use diamonds.
D) Although people may want to use diamonds, they should not use diamonds because there is only one way to draw REA diagrams and that is without diamonds
E) Although people might want to use diamonds to represent relationships, they should in fact be using rectangles to represent the relationships - diamonds are supposed to be used to represent the resources, events, agents, and locations in REA modeling.