Is the answer B?
EDIT: Checked it's B.
So basically whenever the question mentions something about the acid being monoprotic etc, you assume that the acid fully ionises.
So you know: n[NaOH] = c.v = (0.550) x (0.02950) ≈ 0.0162 mol
So assuming full ionisation: n[citric acid] = (n[NaOH]) / 3...