The correct answer is Choice A.
Divide the minimum required load for departure, 4,200 kilograms, by the rate of delivery, 350 kilograms per minute to find the minimum number of minutes to load the truck for departure.
Choice B is incorrect because $18 \text{ minutes} \times 350 \frac{\text{kilogram}}{\text{minute}}$= 6,300 kilograms, which is well over the minimum required load of 4,200 kilograms.
Choice C is incorrect because $35 \text{ minutes} \times 350 \frac{\text{kilogram}}{\text{minute}}$= 12,250 kilograms, which is well over the minimum required load of 4,200 kilograms.
Choice D is incorrect because $42 \text{ minutes} \times 350 \frac{\text{kilogram}}{\text{minute}}$= 14,700 kilograms, which is well over the minimum required load of 4,200 kilograms.
✨ Expert's Tip ✨
Double check your answer by multiplying the time by the rate to find the weight of the load.