In the diagram of the human male reproductive system given below:
$(a)$ Label parts $A$ and $B$.
$(b)$ Name the hormone produced by organ $X$. What is the role of this hormone in the human male?
$(c)$ Mention the name of substances that are transported by tubes:
$(i)$ $C$ and $(ii)$ $D$.

(N/A) is the Seminal vesicle,and $B$ is the Prostate gland.
$(b)$ The hormone produced by organ $X$ (testis) is Testosterone. Its role is to control the formation of gametes (sperms) and regulate the development of secondary sexual characteristics in human males.
$(c)$ $(i)$ Tube $C$ (Vas deferens) transports sperms.
$(ii)$ Tube $D$ (Urethra) transports both sperms (semen) and urine.