AB is divided into 4 equal parts: AP = PQ = QR = RB.
PB = PQ + QR + RB = 3 parts; PQ = 1 part.
So Q divides PB in the ratio 1 : 2. → Option C
From P to B there are 3 equal parts. Q is 1 part from P and 2 parts from B, giving PQ : QB = 1 : 2. Students often confuse this with the ratio relative to the full segment AB — always re-read the segment named in the question (here PB, not AB).