If the function $g(x)=\left\{\begin{array}{cl}\mathrm{K} \sqrt{x+1} &, 0 \leq x \leq 3 \\ \mathrm{~m} x+2 &, 3 < x \leq 5\end{array}\right.$ is differentiable, then $\mathrm{K}+\mathrm{m}=$

• A

  $4$
• Correct answer
  B

  $2$
• C

  $6$
• D

  $0$

Hence, the correct answer is option: 'B'.