Final answer:
To subtract 4.9993m from 700.30m and round to the correct number of significant digits, we need to consider the least precise measurement. The correct answer is 695.30m (option b).
Step-by-step explanation:
To subtract 4.9993m from 700.30m and round to the correct number of significant digits, we need to pay attention to the least precise measurement. In this case, the second measurement, 4.9993m, has five significant figures. Therefore, we round our final answer to the same number of significant figures and keep the decimal point in the same place.
When we subtract 4.9993 from 700.30m, we get 695.3007m. Rounding this to five significant figures, the correct answer is 695.30m (option b).