Final answer:
The answer is D) As many as necessary.
Step-by-step explanation:
The answer to the question 'How many perimeters in Major incidents' is D) As many as necessary.
In mathematics, perimeter refers to the distance around a two-dimensional shape. It is the sum of all the sides of the shape. In major incidents, the number of perimeters can vary depending on the size and shape of the incident. There could be one perimeter, two perimeters, three perimeters, or even more if needed to contain the incident and ensure safety.