sat-dog

Choice A is correct. It’s given that the rocket contained $\mathrm{467,000} \text{kilograms} \text{(kg)}$ of propellant before launch and had $\mathrm{362,105} \text{kg}$ remaining exactly $21$ seconds after launch. Finding the difference between the amount, in $\text{kg}$, of propellant before launch and the remaining amount, in $\text{kg}$, of propellant after launch gives the amount, in $\text{kg}$, of propellant burned during the $21$ seconds: $\mathrm{467,000}-\mathrm{362,105}=\mathrm{104,895}$. Dividing the amount of propellant burned by the number of seconds yields $\frac{\mathrm{104,895}}{21}=\mathrm{4,995}$. Thus, an average of $\mathrm{4,995} \text{kg}$ of propellant burned each second after launch.

Choice B is incorrect and may result from conceptual or calculation errors.

Choice C is incorrect and may result from conceptual or calculation errors.

Choice D is incorrect and may result from finding the amount of propellant burned, rather than the amount of propellant burned each second.