$\text{ Let }f:R\to R\text{ and }g:R\to R\text{ be two given functions such that }f\text{ is injective and }g\text{ is surjective. Then which of the following is injective? }$

• A

  $\text{ gof }$

• B

  $\text{ fog }$

• C

  $gog$

• D

  None of these