In order to contain groundwater, a layer of subsoil must have porosity. that is, it must have empty spaces, or pores. in order to allow groundwater to easily pass through the subsoil, a. the subsoil's pores must be large. b. the subsoil's pores must be connected to each other. c. the subsoil's pores must be small. d. the subsoil's pores must be isolated from each other.