Answer:
"A"
Explanation:
Contract is a legally binding agreement between different parties involved in a business. that means that every party involved must comply with the conditions that guided the formation of the contract , and if violated a legal action can be instituted against the violating party.
Jack's role of cleaning the outside of the restaurant is a substantial performance in the course of the contract. Failure to keep to it does not keep the other parties out of the contract but he can be sued for the for the cost of cleaning.