Answer: Choice A) sqrt(17)
The square root of 17 is irrational because we cannot write this number as a fraction of two whole numbers (see note below). With something like choice B, we can do so and that would be 6/99; while choice C simplifies to 7 which is equivalent to 7/1. Choice D isn't fully visible, but it appears to be a fraction of two whole numbers.
Note: the denominator of the fraction cannot be 0.
