6. X offered to construct the house of Y for a very reasonable price of P2 1 po lillion, giving the latter 20 days within which to accept or reject the offer. in the tenth day, before Y could make up her mind, X withdrew the offer. Which of the following is correct: D a. The withdrawal of X's offer will cause the offer to cease in law; b. If the offer is subsequently accepted, there could be concurrence of the offer and the acceptance; c.X will be held liable to pay Y for damages for withdrawing the offer before the lapse of the period granted; d. The withdrawal is ineffective because it was made before the lapse of the period granted