Ersatz kreme will sell its filling to hunky donuts only if hunky donuts agrees not to buy filling from other suppliers. this is an example of

This is an example of "exclusive dealing".

Explanation:

We can define Exclusive dealing as when one group is working with another group to do any kind of business, at that time the way of dealing is exclusively and they are willing to buy a large number of shares from the first group.

Comprehensively, we can say thay exclusive dealing happens when one individual is exchanging in a deal with another forces a few limitations on the other's opportunity to choose who and where they are dealing.