Let $f, g: \mathbb{R} \rightarrow \mathbb{R}$ be such that $f^{\prime}(x)=g(x)$ and $g^{\prime}(x)=-f(x)$. Let $h(x)=$ $f^2(x)+g^2(x)$. If $h(1)=2018$ then $h(2018)$ is

• A

  $\frac{1}{2018}$
• B

  1
• Correct answer
  C

  2018
• D

  $2018^2$

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