Concept:At puberty, the male hormone testosterone causes changes in boys such as a deeper voice, growth of facial and body hair, broader shoulders and a growth spurt.Solution:The voice box (larynx) grows and the vocal cords thicken, so the voice "breaks" and becomes deeper. This is a change in adolescent males.Widening of the pelvis (hips) happens in adolescent girls, not boys. "Contraction of the pelvis" is not a change of puberty.Height does not stall in adolescence; boys have a growth spurt.Answer:Option A (breaking of voice)