答案：D

题目分析: 句意：老师问学生们他们已经种了多少树。if they are interested in dinosaurs他们是否对恐龙感兴趣，when was Audery Heben born奥代拉.赫本什么时候出生的，What they will do with the computers        他们会用电脑做什么， how many trees they had planted他们已经种了多少树。根据the teacher asked老师问，可知主句为一般过去时，宾语从句时态与过去时态相关，排除AC；宾语从句语序为陈述句语序，排除B，故选D。