Answer:
Because earthworms do not like soil that is too acid, alkaline, dry, wet, hot or cold, their presence is a good indicator of soil conditions suitable for plant growth. Earthworms do not like acid soils with pH (CaCl2) less than 4.5. The addition of lime raises pH and also adds calcium.
C. They study true movement of earthquake waves
State of demographic transition of all countries dictates the growth rate of global population and how close we are to carrying capacity
