Answer: B. Mr. Lanier had a duty to send you a check by the 15th. He's breached that duty under the contract, and it appears to be a material breach, so you have the right to rescind the contract.
Step-by-step explanation:
Material breach occurs when a particular party fails to fulfill his or her part in a contract and this can lead to the other party rescinding the contract or sue for a breach of contract.
Since under the terms of the agreement, Mr. Lanier has to forward a certified check for 25% of the purchase price within 15 days of the signing of the purchase agreement but he didn't send the check, this means that the there's a breach in the contract, and the contract can be rescinded.