Final answer:
Option D is correct option. When adding 4.02 and 0.001 according to significant figures rules, the sum must be rounded to two decimal places because 4.02 is the least precise term. The correct rounded result is 4.02.
Step-by-step explanation:
To calculate 4.02 + 0.001 using significant figures, we must consider the number of decimal places in the numbers being added. The number 4.02 has two decimal places, while 0.001 has three. According to the rule of significant figures for addition, the result should be rounded to the least number of decimal places of any number in the operation. Therefore, the correct answer is rounded to two decimal places.
The resulting sum is 4.021 before rounding. Applying significant figures rules, we round it to match the least precise term, which is 4.02, with two decimals. Hence, the final answer in significant figures is 4.02 which corresponds to option D.