CAN is mainly useful as which type of fertilizer application?

Answer: Option B

CAN is calcium ammonium nitrate, also known as nitro-limestone or nitrochalk. It is a widely used inorganic fertilizer, accounting for 4% of all nitrogen fertilizers used.
It is hygroscopic, and its dissolution in water is endothermic. It accounts for roughly 8% calcium and 21 - 27 % nitrogen. It is preferred for use on acidic soils. it is mainly useful as a Top dressing for fertilizer application.