The answer is -π
If you add π + (-π), you get 0 which is a rational number.
Adding 2 only results in changing the 3.14... to a 5.14... which is still an irrational number.
Adding 1/π only results in adding 1/3.14... to π which equals 3.45... which is still an irrational number.
Adding 0 doesn't change the original value at all so its still an irrational number.
Therefore, -π is the only logical answer.
Best of Luck!