Toxins are non-living biological agents produced by living plants, animals, or bacteria. an example of a toxin is:

Botulinum toxin

Toxins are non-living biological and chemical agents produced by living microorganisms from animals and plants that can cause harm to humans, plants and animals. An example of toxin is botulinum toxin produced by the bacterium Clostridium, which is a neurotoxic protein that prevents the release of the neurotransmitter acetylcholine from axon endings at the neuromuscular junction and causes flaccid paralysis.

Moreover, toxin are more closely related to chemical warfare agents that can only affect those who are exposed to the agent and that they are not considered as transmissible disease.

as the gila monster consumes the eggs or young of the desert cottontail and gambel's quail, thus its main food supply is only accessible for a restricted time duration every year. however, for this, the gila monsters exhibit three adaptations, which elevate their survival rate in the desert condition.  

first, is that they possess huge bodies, and can consume greater concentrations of food during a small period. secondly, they require to feed infrequently as they can accumulate fat in their tails. ultimately, their rate of metabolism is very low, so that they can burn their reservoirs of fat gradually.  

b. lithosphere, asthenosphere, mesosphere   is the answer most likely