Assertion $(A)$: Covalent character follows $NaCl < MgCl_2 < BeCl_2 < LiCl$.
Reason $(R)$: According to Fajan's rules,covalent character of ionic compounds increases with decrease in size of cation.

• A
  Both $A$ and $R$ are true and $R$ is a correct explanation for $A$.
• B
  Both $A$ and $R$ are true but $R$ is not a correct explanation for $A$.
• C
  $A$ is true but $R$ is false.
• D
  $A$ is false but $R$ is true.