Question 4
Of the changes listed in males at adolescence, only one is reproduction itself rather than appearance. Which is it?
The right answer is the one marked above.
The production of sperm beginning in the testes. This is what the hormone is for; everything else follows from it as a side effect.
Broad shoulders, a deep voice and body hair are secondary in the literal sense — driven by the same testosterone, but not the point of it. The same pattern holds in females, where only the start of the menstrual cycle is reproduction itself.