Select the correct statement for Zeise's salt:

The correct statement for Zeise's salt is $\mathrm{C}-\mathrm{C}$ bond length of ethylene is higher in complex than $\mathrm{C}-\mathrm{C}$ bond length of ethylene in isolated conditions.

Zeise's salt $\left.\to {\mathrm{KIPtCl}}_3\left({\mathrm{C}}_2{\mathrm{H}}_4\right)\right],{\mathrm{C}}_2{\mathrm{H}}_4$ is perpendicular to the Pt-square complex's plane. A result of the back bonding ${\mathrm{\pi }}^{°}$ of  B.L. ${\mathrm{C}}_2{\mathrm{H}}_4,\mathrm{C}-\mathrm{C}\text{ B.L. }\uparrow$

Hence, option B is correct.