If two sides of the 10-sided die are red, the probability that, on any given roll, the die lands red-side up is 1/5. If Kumar rolls the die three times and gets a red side up for the first time on the third roll, that means he rolled it twice and some other color came up the first two times.

If the probability the die lands red-side up is 1/5, the probability that it DOESN'T land red-side up is 1 - 1/5 = 4/5. What we're looking for is the probability it landed some other color up, then some other color up again, then red side up. As a probability, that's:
(4/5)(4/5)(1/5)
= 16/125
To simplify that fraction, recognize that 125 is 1/8 of 1,000, so:
= (16/125)*(8/8)
= 128/1000
= 0.128, choice (C).