The correct option is
B 43.632
In 21.455, the digit in the thousandths place is 5.
So, this will round up the hundredths place to 6.
Hence, the rounded number is 21.46.
In 43.632, the digit in the thousandths place is 2, which is less than 5.
So, this will round down the hundredths place to 3.
Hence, the rounded number is 43.63.
However, it is calculated as 43.65 in the question, which is incorrect.
In 57.828, the digit in the thousandths place is 8, which is more than 5.
So, this will round up the hundredths place to 3.
Hence, the rounded number is 57.83.
Hence, the decimal number that is incorrectly rounded is 43.632.