First, let's find the correct exponent. We have 8 digits after the first digit (2), therefore the exponent will be 8. So, the correct answer must be among the first two options.
To understand which one is correct, let's have a look at the digits after 2. We have: 9979. If we want to round this number, it will be 998, because after the 7 we have a digit which is larger than 5, so 7 must be rounded to 8. Therefore, the correct number will be:
