Answer:
If the offer is rejected by the Dall then the offer is no more in place. The particular reason is that Martin is not required to tell Dall that the offer is no more in place. Suppose Martin is wishing to close his offer and till now Dall has not declined the offer. So Martin will have to communicate Dall that the offer is been closed. If Dall has communicated Martin that he has rejected the offer, then this means the offer essence has vanished. Hence Martin has no liability towards Dall, if Dall sues him.