An activity that is sustainable is best described as one that works to maximize species richness
is a net positive activity (does more good than harm)
does not involve resource extraction or produce pollution
does not negatively impact the lives of others
O can be carried out indefinitely into the future

option c is the correct answer.

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.

a covalent bond, specfically triple bond