The answer is: the source of information could be biased
The scientist is interviewing environmentalists and then generalized their opinion as "people". An environmentalist is a person that cares about the environment, so they will more likely to deny the option that harms the environment. If the dam harmful to the environment, most environmentalists will not approve it.
i think is
The predators’ survival depends on biotic factors.
Water logged? If the soil does not stick together the soil will seperate and water will have easier access to enter
The effect of a neurotransmitter is based on the properties of the receptor more than the neurotransmitter.
The structure is calcium ions.