Parents should take seriously their children' s requests for sunglasses______eye protection is necessary in sunny weather.
【正确答案】 A
【答案解析】because：因为，引导原因状语从句，符合题意；though：虽然，即使，引导让步状语从句；unless：如果不，除非；if：如果，假使，引导条件状语从句。本题空处前后两个分句为因果关系。故选A。