Which best describes a scientific theory? * A) A well-established and highly reliable explanation of a phenomena or situation.
B) Based on many many observations and investigations over time
C) A casual idea
D)Both A and B

the wires in the toaster turning red and the toast crisping and turning brown

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.