Answer:
The correct answer is B. 2π
Explanation:
A rational number is one that can be represented using a fraction and an irrational number cannot be represented using a fraction.
-√4 = -2, which is a rational number
2π is not a rational number (we cannot express pi as a fraction exactly even though there are some close approximations)
2.2121... is also a rational number because it can be expressed as a fraction (21/99, or 7/33 simplified)
√225 is 15, which is a rational number
Therefore, the only irrational option is option B. 2π, which is your answer.
Hope this helps!