What is the $Tunica \text{ } albuginea$ a covering of?

Given below is a diagram of the $T.S.$ of a testis. Select the option which gives the correct identification of the function of cells labeled $A, B, C,$ and $D$ from the options given below.
$A$ - cells undergo spermatogenesis to produce spermatozoa.
$B$ - cell responsible for the development of male secondary sexual characters.
$C$ - heads of sperms remain attached to these cells.
$D$ - haploid male gamete.

Cryptorchidism is a condition in which

Describe the structure of a seminiferous tubule.

The primary sex organ in man is:

Identify the parts $a, b, c, d$ in the given diagram of the male reproductive system.