You observed many sand hill cranes on your walk. Two sand hill cranes flapped their wings and hopped up and down when you walked on the path near where their bright orange baby stood. You observed a(n) .

Group of sandhill cranes living together, best explains that you observe a population of sandhill cranes.

Population:

In ecology, a population is a group of living organisms of the same species have the ability to interbreed and usually found in a similar habitat.

Here,  

Sandhill cranes were observed in their habitat. Sandhill cranes are found in groups, living together.  So it is most likely to see a population of sandhill cranes.  

Therefore, group of sandhill cranes living together, best explains that you observe a population of sandhill cranes.

To know more about Population,

link

This question lacks options, the options are:

A) symbiosis

B) ecosystem

C) community

D) population

E) biosphere

The answer is D) Population

Explanation:

In ecology, a population refers to the group of living organisms of the same species living together in the same habitat and have the ability to interbreed i.e. mate and reproduce fertile offsprings.

In this question where many sandhill cranes (large flying birds) were observed in their habitat. In addition to the fact that the group of sandhill cranes are found to be living together, they were also observed to be reproducing with other members of the population. This was portrayed by the observation of two sandhill cranes hopping up and down around their bright orange baby. This shows that members of the population are capable of mating and reproducing fertile offsprings.

This observation i.e group of sandhill cranes living together and interbreeding, best shows that the observed is a POPULATION of sandhill cranes.