题目选项分析

The ice on the front windshield of the car had formed when moisture condensed during the night. The ice melted quickly after the car was warmed up the next morning because the defrosting vent, which blows on the front windshield, was turned on full force.

Which of the following, if true, most seriously jeopardizes the validity of the explanation for the speed with which the ice melted?

【选项】Even though no attempt was made to defrost the back window, the ice there melted at the same rate as did the ice on the front windshield.