( ) those pictures, she couldn't help thinking of the happy da

( ) those pictures, she couldn't help thinking of the happy days.
A、Seeing
B、To see
C、Seen
D、Have seen
【正确答案】：A
【题目解析】：考核分词做状语，句子含义为看着这些照片，她不禁回忆起美好的日子。