At its melting point ice is lighter than water because

Given below are two statements .
Statement $\mathrm{I}$ : In ${\mathrm{CuSO}}_4·5{\mathrm{H}}_2\mathrm{O}, \mathrm{Cu}-\mathrm{O}$ bonds are present.

Statement $\mathrm{II}$ : In ${\mathrm{CuSO}}_4.5{\mathrm{H}}_2\mathrm{O}$, ligands coordinating with $\mathrm{Cu} \left(\mathrm{II}\right)$  ion are $\mathrm{O}$-and $\mathrm{S}$-based ligands.

In the light of the above statements, choose the correct answer from the options given below

Statements about heavy water are given below.

A. Heavy water is used in exchange reactions for the study of reaction mechanisms.

B. Heavy water is prepared by exhaustive electrolysis of water.

C. Heavy water has higher boiling point than ordinary water.

D. Viscosity of ${\mathrm{H}}_2\mathrm{O}$ is greater than ${\mathrm{D}}_2\mathrm{O}$.

Choose the most appropriate answer from the options given below:

In reference to water, choose the correct statement

(i) It gets oxidised to ${\mathrm{O}}_2$ during photosynthesis.

(ii) It gets reduced to ${\mathrm{H}}_2$ by highly electropositive metal.