8. Which of the following is the disadvantage of contour system? a. Laying out of contour line is difficult and time consuming b. Contour system can control the soil erosion c. It helps simultaneously in the conservation of water. d. It can be adopted in hilly regions and in leveled land. 9. A system where the trees are planted at the corners of an equilateral triangle a. Contour system b. Hexagonal system c. Quincunx system d. Square system 10. What do you call the additional tree in the center of a quincunx system? a. Filler b. Grower Filter d. Shelter C.​