单选题 The officers made it clear that they were letting her go only {{U}}because{{/U}} that she was old and not because she was above suspicion.

A、 for reason
B、 due to
C、 because of
D、 on the grounds

【正确答案】 D

【答案解析】[分析] 近义词辨析。 because因为(引导原因状语从句)；for reason应为for the reason that；because of和due to后应接名词性短语，on the grounds根据，以……为理由，(如后跟短语，用on the grounds of；如跟从句，用on the grounds that)；因此D为答案。