Answer:
The correct option is D: Only one promise is involved if the contract is unilateral but two if bilateral.
Explanation:
While bilateral contracts and unilateral contracts are both enforceable in a court of law, a unilateral contract has only one promise, which means that as long as someone decides to fulfill the act that the promisor demands, a contract is formed. On the other hand, a bilateral contract is on enforceable when the two parties are bound in the promise.