Answer:
None of the above
Explanation:
We have to find irrational number in given options.
Rational number: That number which can not written as
where p and q are integers,

Irrational number: The number which is not a rational number then, the number is called irrational number.
A.9
9 is an integer .Therefore, it belongs to rational number set not irrational number set.
So, it is false.
B.27
27 is an integer number.Therefore, it belongs to rational number set not irrational number set.
So, it is false.
C.36
36 is an integer number.Therefore, it belongs to rational number set not irrational number set.
So, it is false.
D.81
81 is an integer number.Therefore, it belongs to rational number set not irrational number set.
So, it is false.]
Answer: none of the above