A: This is an acidity question in disguise. The first question is, which H's are the most acidic (Slide 2)? Replace all of these with D.
To figure out which H is most acidic, test out removing the H's in question and looking at the stability of the product. Keep an eye out for resonance structures and conjugation, a sure sign of stability. Check your structures in slide 3.
Check slide 4 for the answer.