Consider How the NMR Spectrum of Protons a in the Compound

Multiple Choice

Consider how the NMR spectrum of protons a in the compound changes on the addition of a trace of acid (assume that J_ab ≠ J_ac) :

A) no change
B) from a doublet of doublets to a simple doublet
C) from a triplet to a singlet
D) from a doublet of doublets to a triplet
E) none of these choices