Which of the following statements is true?

a. the lower the number of living organisms in an area, the higher the rate of weathering will be.

b. rocks rich in calcium, potassium, and sodium, weather into fertile soil.

c. raindrops and snowflakes are too light to cause erosion.

d. wind erosion removes the least fertile part of soil.

step 1: nitrogen fixation- conversion of atmospheric no₂ into forms useful to plants by lightning, bacteria, and cyanobacteria.

step 2: nitrification-process of converting ammonia to nitrite or nitrate.

step 3: assimilation-plant roots absorb new form of nitrogen.

step 4: ammonification-conversion of organic nitrogen to ammonia by bacteria involved in decomposition.

step 5: denitrification-bacteria turns the decomposed matter back into n₂o, which is released into atmosphere; repeat cycle.