What is the concept of rounding decimals? be certain to leave an example

Look at the digit to the right of the required number. If it is a 5 or greater, add 1 to previous digit.
If it is less than 5, leave the previous digit unchanged. In either case, drop all the remaining digits. Example: Round off this decimal 7.253896 to three decimal digits.
Answer. 7.253896approximately7.254
(The wavy equal sign approximately means "is approximately equal to.")
To round off to three decimal digits, we must look at the digit in the fourth place. The digit in the fourth place is 8 (greater than 5). Therefore, we add 1 to the previous digit 3.

Distance=slopeslope is -2/4which equals-1/2the distance between these two points is -1/2

Ithink the answer is c