Which of the following are examples of the ways erosion affects the environment? i. erosion introduces pesticides and toxins into waterways, causing pollution. ii. polluted waterways decrease biodiversity. iii. eroded soil allows sediment to break off and clog waterways. iv. eroded soil becomes useless for agriculture. a. i. only b. i. and ii. c. i., ii., and iv. d. i., ii., iii., and iv.