The metallic sodium dissolves in liquid ammonia to form a deep blue coloured solution. The deep blue colour is due to formation of :

Question

( A ) solvated atomic sodium, $Na(NH_3)_y$
( B ) solvated electron, $e^- (NH_3)^-_x$
( C ) $NaNH_2 + H_2$
( D ) $(Na^+ + Na^-)$