The little girl felt upset her pet dog died.A. why B. because of C. because

问题补充：

The little girl felt upset her pet dog died.

A. why B. because of C. because

答案：

解析：

这题考查原因状语从句的用法：because引导原因状语从句，句意是：因为宠物狗死了，小女孩感到难过。Because of是介词短语，后面是接名词。