Covalent radius of $\mathrm{Cl}$ is 99 pm. Select beat representation for ${\mathrm{Cl}}_2$  molecule :

When two atoms' parallel orbitals of the same atom overlap, a covalent bond is created. So, in essence, covalent radius is equal to half of the distance between two atoms' nuclei. 

$\begin{array}{r}\frac{d}{2}=r_2\\ d=2\times 99=198\mathrm{pm}\end{array}$

Therefore, the right response is (C).