Given below are the statements about diborane.
$(a)$ Diborane is prepared by the oxidation of $NaBH_{4}$ with $I_{2}$.
$(b)$ Each boron atom is in $sp^{2}$ hybridized state.
$(c)$ Diborane has one bridged $3$ centre$-2-$electron bond.
$(d)$ Diborane is a planar molecule.
The option with correct statement$(s)$ is :

• A
  $(c)$ and $(d)$ only
• B
  $(c)$ only
• C
  $(a)$ only
• D
  $(a)$ and $(b)$ only