Identify the cells representing $P$,$Q$,$R$,and $S$ in the given schematic representation of spermatogenesis.

• A
  $P$ - Spermatozoa,$Q$ - Spermatids,$R$ - Secondary spermatocyte,$S$ - Primary spermatocyte
• B
  $P$ - Primary spermatocyte,$Q$ - Secondary spermatocyte,$R$ - Spermatids,$S$ - Spermatozoa
• C
  $P$ - Secondary spermatocyte,$Q$ - Spermatids,$R$ - Spermatozoa,$S$ - Primary spermatocyte
• D
  $P$ - Secondary spermatocyte,$Q$ - Primary spermatocyte,$R$ - Spermatozoa,$S$ - Spermatids