The correct response for Justin to find the product of $1.39 and 100 is:
He knows that 100 is 10 to the power of 2, so he needs to move the decimal point in 1.39 two places to the right.
This is because multiplying by 100 (which is \(10^2\)) means you move the decimal point two places to the right. Therefore, multiplying $1.39 by 100 gives:
1.39 * 100 = 139.00 or $139.00.