In group $13$ of the long form of the periodic table,an element $X$ has a boiling point of $T_2 \ (K)$ and a melting point of $T_1 \ (K)$. Identify the element $X$ for which $T_2 - T_1 \ (K)$ is maximum.

• A
  $Al$
• B
  $Ga$
• C
  $In$
• D
  $B$