I’ll go ahead and claim F.
Transcription
《私は研究『に』戻ります》
I think I can tell the meaning of this one at a glance but for thoroughness sake:
Vocabulary
私『は』: pr. 1st person + topic marker;
研究【けんきゅう】n. studies;
『に』indicates the receiver if an action/destination;
戻ります【もどります】v. to return, to go back;
Interpretation
I’ll return to my studies.