Answer
b. \$83.
Work Step by Step
The formula for the present value to be paid is $X/(1+r)^N$, where $X$ is the present value, $r$ is the interest rate, and $N$ is the number of years.
$100/(1+0.1)^2 = 100/1.21 = 83$
The present value of \$100 to be paid in two years is \$83.