Explain your thinking Describe the 'rule' or reason you used to decide whether something
is or is not matter.

I'm not sure if this is what you're looking for, but if a substance has mass and volume, it's matter. Plain and simple haha.

the answer would be 3

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.