These are all receptors that react to certain kinds of stimuli. The chemoreceptors react when there are changes in chemical concentrations within the body; the mechanoreceptors detect pressure or distorted stimuli; and the nocioreceptors send signals of pain to the spinal cord and brain.
Spicy food actually does not have a specific location in the taste buds of the tongue. This is the reason why it is not considered a flavor but rather a sensation. Spicy food stimulates the release of chemicals and signals to the brain which are detected by these different kinds of receptors.
You want to avoid doing D at all cost. It's important that your friend doesn't feel that your friendship is in danger. That may only encourage her to enduce more self harm.
It will screw the food web up because invasive species can take over and kill other species therefore eliminating one or more food sources that that environment had.
