The correct answer is: D. Sand and sodium bicarbonate
Dry powder fire extinguishers contain a fine powder that is used to smother a fire. The powder is made of a mixture of sodium bicarbonate (baking soda) and other chemicals. When the powder is released from the extinguisher, it forms a cloud that surrounds the fire. The powder blocks the oxygen that the fire needs to burn, and it also coats the fuel, making it difficult for the fire to spread.
Sand is not an effective fire extinguishing agent. It is too coarse to form a dense cloud, and it does not block oxygen as effectively as powder. Potassium carbonate is also not an effective fire extinguishing agent. It is a salt, and it will react with water to form a base. This base can be corrosive, and it can also damage electrical equipment.
Sodium bicarbonate is an effective fire extinguishing agent. It is a base, and it will react with acids to form salts. This reaction releases heat, which can help to extinguish a fire. Sodium bicarbonate is also non-toxic and non-corrosive, making it safe to use around people and equipment.