Which of the following statement is correct ?

• A

  $\text{ A }\mathrm{\sigma }\text{-bond is weaker than a }\mathrm{\pi }\text{-bond. }$

• B

  $\text{ There are four co-ordinate bonds in the }{\mathrm{NH}}_4^{+}\text{ion. }$

• C

  The covalent bond is directional in nature.

• D

  HF is less polar than HCl.