A square field has its area equal to 324 m². The perimeter of the field is:

The correct option is 72m.

To find the perimeter of a square field, we first need to determine the length of one of its sides from the given area.

Let $a$ represent the side length of the square field.
The formula for the area of a square is given by:

$\text{Area}=a^2$

We are given that the area of the field is 324 m². Substituting this value into the formula:

$a^2=324$

Taking the square root of both sides to find the side length $a$:

$a=\sqrt{324}$

$a=18\text{m}$

Now that we have the side length of the square field, we can calculate its perimeter.
The formula for the perimeter of a square is:

$\text{Perimeter}=4\times a$

Substituting $a=18\text{m}$ into the perimeter formula:

$\text{Perimeter}=4\times 18$

$\text{Perimeter}=72\text{m}$

Thus, the perimeter of the square field is 72 m.