The correct way to move the decimal to find the quotient is b. two places to the right.
This is because 100 has two zeroes in it, so you know that you have to move the decimal either two places to the right or two places to the left.
100 is a positive number, and when multiplied by a positive number with a decimal, it makes an even larger number. So, you would move 23.8 decimal place two places to the right.