Problem:
On June 1st the Mega Marketing Research Firm sent out a mail survey to * 2 point 5,000 potential customers of Mega's client company. The survey stated that everyone who completed the survey and mailed it back would receive a prize. Mega did not expect everyone to respond to the survey and had only 1,000 prizes on hand for the respondents. On July 14th Sam mailed back his response and eagerly awaited his prize. On July 15th Mega sent out the last prize it had. Sam's response arrived on July 16th. It was the 1001st and Mega wrote back telling Sam that unfortunately all the prizes were gone, and he would not be able to have one.
O No contract was formed here as there was no communication of Sam's acceptance before Mega's offer lapsed.
O Mega had essentially revoked its offer before Sam accepted.
O A valid contract was formed between Mega and Sam.