A population of beetles is kept in a controlled ecosystem. No beetles are allowed to enter or leave. The graph below shows the population of beetles.
Beetle Population
с
Population size
"B
В
A
Time
Which best describes the ecosystem at Point A?
ye
O
A. The death rate is higher than the birthrate.
о
B. Population growth is slowing down.
O
C. There are plenty of resources.
D. It has reached carrying capacity.

C

Explanation:

It is not A, A would see a decline or downward arrow in the population

It is not B, B would see the upward trend becoming longer horizontally / becoming slower

It is not D, D would be the red dashed line

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.