17. Which of the following statements is true?
a. There is a no supply of energy from the Sun.
b. Matter cycling does not provide us the nutrients necessary to live.
c. Gravity keeps these nutrients within our reach.
d. All of the above
18. Which of the following is/ are producers
a. Grass b. Trees c. Flowering plants d. All of the above
19. It refers to a series of interconnected food chains
a. Food web b. Food pyramid c. Energy pyramid d. None of the above
20. Anthropogenic activities are also called
a. Human activities b. Natural disasters c. artificial d. done by nature​