HELP WITH ORGANIC CHEMISTRY TBR CHAPTER 1 QUESTION

Hi all, I started studying organic chemistry today using TBR and got 15 out of 25 questions wrong. Pretty bummed about it. Anywoo, While reviewing the exams I realized I wasn't reading some of the questions correctly or wasn't paying attention to resonance structure or just didn't know the stuff so I guessed(the IR stuff). My particular question is about Question 12( I tried uploading a picture but it said it was too large)

Can someone explain why the answer is option D and how do I know...

HELP WITH ORGANIC CHEMISTRY TBR CHAPTER 1 QUESTION