An element \( A \) of group \( 1 \) shows similarity to an element \( B \) belonging to group \( 2 \). If \( A \) has maximum hydration enthalpy in group \( 1 \) then \( B \) is:
\( \mathrm{Mg} \)
\( \mathrm{Be} \)
\( \mathrm{Ca} \)
\( \mathrm{Sr} \)