Given below are two statements. Select the most appropriate answer from the given options.
Statement-$I$: $T$-lymphocytes have $4$ subtypes as helper,killer,memory,and suppressor $T$-cells.
Statement-$II$: $B$-lymphocytes mature in the thymus and are responsible for cell-mediated immunity.

• A
  Statement-$I$ is correct but Statement-$II$ is incorrect.
• B
  Statement-$I$ is incorrect but Statement-$II$ is correct.
• C
  Both Statement-$I$ and Statement-$II$ are correct.
• D
  Both Statement-$I$ and Statement-$II$ are incorrect.