Final answer:
When adding numbers with different significant figures, match the least precise decimal position. The sum of 87.3 and 0.001 reported to the correct significant figures is 87.3.
Step-by-step explanation:
When adding 87.3 and 0.001, the result must be reported with the correct number of significant figures. The number 87.3 has three significant figures, and 0.001 has only one significant figure. However, in addition and subtraction, the decimal precision of the least precise number should be matched. Therefore, we keep the decimal precision to the tenths place since 87.3 is only precise to the tenths place. The correct answer is B) 87.3.