Which of the following statement is related with the 'Sulphur shower'?

• A. Discharge of large quantities of Crocus (yellow kesar) pollen grains into the air.
• B. Discharge of large quantities of pinus pollen grains into the air forming yellowish clouds.
• C. Release of a large amount of sulphur particles into the air from factories processing sulphur.
• D. Release of a large amount of sulphur particles into the air near sulphur mines.