It was not until she had arrived home ________ remembered ________ the key in her office．
A.when she; to leaveB.and she; leavingC.that she; leavingD.she; to leave在线课程C
解析：
从句型来看，第一空处填that，构成not until的强调句；
remember doing sth。表示“记得做过某事”。