Answer: Option 'A' is correct.
Step-by-step explanation:
Since we have given that
Rational numbers are those numbers which can be written as p/q form or it must be non terminating but recurring number.
-13 can be written as p/q form as 
is a rational number because of its form.
81 can be written in p/q form as 
But √2 is non terminating and non recurring number.
Hence, √2 is not a rational number.
Therefore, Option 'A' is correct.