Answer:
-√36
Explanation:
The first (approx. 3.567) is obviously irrational, as it continues forever; the decimal values do not end.
The next (√18) is approx. 4.243 and is irrational.
The next (π/3) is irrational because it involves an irrational number, π.
The last (-√36) is -6 and is therefore rational.