Which of the following imparts green/apple green colour to the Bunsen flame?

The Bunsen flame's colour is green or apple green because of the volatile boron trifluoride, barium chloride, and ethyl borate.

Green is added to the flame by$"{\mathrm{BF}}_3",\mathrm{B}{\left({\mathrm{OC}}_2{\mathrm{H}}_5\right)}_3$, and Barium chloride (volatile)," which gives the flame an apple green hue.

Hence correct options are b, c, d