The correct answer is the first one
Its 80 because if you find perfect square around the number 80 you'd get
√64 and √81
which would be 8 and 9
Lets test out all the answers
A. 2/3 is about .666 so A is not
B. 3/5 is .75 so B is B also not
C 7/9 is 0.7777 which is still less so C is not
D. 4/5 is about 0.80 and this is more than 0.78 so D is the answer
True
An easy way to tell if a number is irrational if you cannot count it, or convert it into a decimal/fraction.
Such as pie, square root of 11, etc.