Answer:
She did not choose a suitable time and place to address the conflict.
Step-by-step explanation:
Conflict management is the process by which two or more parties resolve differences between them.
They need to dialogue and express their misgivings in the situation so that an equitable solution can be agreed upon.
In the given instance Diane has become concerned that Gretchen is eating the majority of the groceries, but still only paying for half.
This is a conflict that needed to be resolve. However she brought up the discussion when they are at the grocery store checkout and Gretchen asks Diane to pay for her half.
Diane should have brought up the discussion before they came to the store.
So she did not choose a suitable time and place to address the conflict.