Arrange the following layers of flexible pavement in sequential order (from bottom to top). Surface course, Subgrade course, Subbase course, Base course
1
Surface course, Subgrade course, Base course, Subbase course
2
Subbase course, Base course, Subgrade course, Surface course
3
Subgrade course, Subbase course, Base course, Surface course
4
Base course, Subgrade course, Subbase course, Surface course