(A) 12.5 cm
Since PQ ∥ YZ, by BPT (Thales Theorem): $\dfrac{XP}{XY} = \dfrac{PQ}{YZ}$
$XP:PY = 2:3$, so $XY = XP + PY = 5$ parts, giving $\dfrac{XP}{XY} = \dfrac{2}{5}$
$$YZ = PQ \times \frac{XY}{XP} = 5 \times \frac{5}{2} = 12.5 \text{ cm}$$
Since PQ ∥ YZ, triangles XPQ and XYZ are similar (AA criterion — same vertex angle X, corresponding angles equal). The ratio of similarity is $\dfrac{XP}{XY} = \dfrac{2}{5}$, so $\dfrac{PQ}{YZ} = \dfrac{2}{5}$, giving YZ = 12.5 cm. Remember: always find the ratio of the full side (XY), not just XP to PY.