Correct Answer - B
Dilute solutions of alkali metals in liquid `NH_(3)` are dark blue in color and contain ammoniated metal ions and ammoniated electrons :
`M+(x+y)NH_(3)to M^(+)(NH_(3))_(x)+e^(-)(NH_(3))_(y)`
When light falls on ammoniated electrons, they get excited to higer energy levels by absorbing the red part of visible light. As a result, the transmitted light is blue imparting blue color to the solution.
