The answers are B, E and H.

The sentence describes how human-caused disturbances individually may not be sufficient to cause a population crash, but their combination could lead to declines. The sentence also emphasizes the importance of studies focusing on individual factors rather than overlooking potential interactions.

Blank (i):
A. delay: Delay means to postpone or defer. In the context of the sentence, it doesn't align with the idea of causing a population crash.
B. trigger: Trigger means to cause or initiate. This term fits well with the context, suggesting that each adverse human pressure is in itself insufficient to initiate a population crash.
C. offset: Offset means to counterbalance or compensate. This term doesn't align with the idea of causing a population crash.

Blank (ii):
D. integrate: Integrate means to combine or bring together. In the context of the sentence, it doesn't align with the logic of focusing on individual factors.
E. focus on: Focus on fits well with the idea that studies of population declines should concentrate on individual factors.
F. ignore: Ignore means to disregard or neglect. This term does not align with the context.

Blank (iii):
G. exaggerate: Exaggerate means to represent something as being greater or worse than it really is. In the context of the sentence, it doesn't align with the idea of properly managing declining species.
H. overlook: Overlook means to fail to notice or consider. This term fits well with the idea that studies focusing on individual factors may lead to neglecting potential interactions.
I. anticipate: Anticipate means to expect or predict. In the context of the sentence, it doesn't align with the idea of improper management of declining species.