Humans can cause an ecosystem to collapse by
a. collecting and chemically altering industrial waste to detoxify it.
b. reducing habitat fradmentation.
c. hunting a keystone species to extiction.
d. building shelter belts next to farm fields.

C.Hunting a keystone species to extinction.

Explanation:

The ecosystem is an interaction of living beings with their non-living physical environment. The living organisms interact among themselves so as to sustain their lives.

The human beings are responsible for the collapse of ecosystem by their interventions and ill-legal activities. The keystone species is the one on which the other species of the ecosystem are dependent upon for their survival. If the keystone species are hunted at an level of extinction this is likely to affect other species of the ecosystem and will negativity affect their diversity.  

c.) polymerase chain reaction

- "unlike the original dna fingerprinting method, dna profiling does not use restriction enzymes to cut the dna. instead it uses the polymerase chain reaction (pcr)? to produce many copies of specific str sequences. pcr is an automated procedure that generates lots of copies of a specific sequence of dna."

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