Fact Pattern 7-2 Hester Offers to Sell Her House to Frank for $250,000

Fact Pattern 7-2
Hester offers to sell her house to Frank for $250,000. Frank says that he would like to think about it, and Hester says that is fine. The next day, Martha, Hester's friend, says that she will give Hester $240,000 for the house. Hester really likes Martha more than Frank and signs a contract to sell the house to Martha. Later that day Hester sees Frank walking up her driveway. She immediately opens the window and yells "I revoke the offer on the house" before Frank says anything. Frank replies that he accepts the offer and expects to purchase the home. Frank tells Hester that while he has not yet taken steps to sell his own home or get a loan, he feels confident that there will be no problem with those matters and he is a ready, willing, and able buyer.
-Refer to fact pattern 7-2. Which of the following is true regarding whether Hester's attempted revocation was effective?

A) It was effective because Hester had left the offer open the amount of time required by law regardless of whether she revoked before Frank could accept.
B) It was effective because Hester issued the revocation before Frank could accept.
C) It was ineffective because the amount paid by Martha was less than the offer to Frank.
D) It was ineffective because Hester attempted the revocation at too early a point in time.