The correct answer is D. Field.
A field is an open area of land, typically with some vegetation, that is used for agriculture or grazing. A forest is a large area of land covered with trees and other plants. A lawn is a piece of ground covered with grass, especially one that is kept mowed and tidy. A garden is a piece of land where plants are grown for food, or for their beauty. A park is an area of land that is kept for public use, typically with gardens, lawns, and trees.
The relationship between tree and forest is that a forest is a large area of land that is covered with trees. The relationship between grass and field is that a field is an open area of
land that is covered with grass.The other options are not correct because they do not have the same relationship to grass as forest does to tree. A lawn is a piece of ground covered with grass, but it is not typically a large area. A garden is a piece of land where plants are grown, but it is not typically covered with grass. A park is an area of land that is kept for public use, but it is not typically covered with grass.