A circular field and a square field are considered equivalent if they have:

Equivalent fields in geometry are typically evaluated based on their area. When a circular field and a square field are considered equivalent, it means they occupy the same amount of space, which is determined by their area.

For a circle, the area is calculated using the formula A = πr², where r is the radius. In contrast, the area of a square is determined using the formula A = s², where s is the length of a side. When the areas of these two shapes are equal, they can be deemed equivalent regardless of their shape or perimeter.

While options related to perimeter, depth, and radius may reflect attributes about the fields, they do not define equivalency in terms of the physical space that the fields occupy. Thus, the equivalence based on area provides a comprehensive understanding of their size and capacity, which is fundamental when assessing geometric shapes.