【正确答案】 1、D    

【答案解析】从Gwendolyn的第四句话…children often worry about the other parent．及第五句话…younger children to return to earlier behavior such as thumb sucking，clinging to blankets and other security object、和第六句话Older children are more likely to respond with feeling of insecurity and anger．可以知道单亲家庭的孩子会产生忧虑、不安全等情绪，如吮吸大拇指，怀抱毛毯等物就是孩子没有安全感的行为表现。