1. its (b)
2. Blue zone: It is near the base of the flame. Here the fresh air rapidly mixes with was vapour formed from the molten wax.A part of wax vapour completely burns and gives rise to blue flame.
3. Elements in the first 2 groups and copper are observed to produce colored flames when heated sufficiently. This is because their electrons are excited by the added energy and move to a higher energy level. As they return to their original energy level they emit the energy in the form of light.