题目选项分析

In Arumville, among those young children with elevated levels of lead in their blood, few live in houses containing lead-based paint, but many live in areas where vehicular traffic is heavy. These children's elevated blood-lead levels probably result from lead added to gasoline, since, although gasoline sold in and around Arumville has been lead-free since 1990, lead from vehicle exhaust remains in the soil for many years.

Which of the following, if true, most strengthens the argument?

【选项】In Arumville, children's blood-lead levels typically rise during the warm summer months when children frequently play outdoors but not in the winter when children spend more time indoors.