To treat the callus, you decide to shave off some of the excess epidermis. While doing this, you notice that there is no pain or bleeding. Why wouldn't it cause pain to remove the superficial layers of the epidermis? Why wouldn't it bleed?

the relative standard reduction potential of the half-cell in which reduction occurs; more positive than the other half-cell. reduction is a chemical process in which electrons are added to an atom or an ion; it always occurs accompanied by oxidation of the reducing agent.

i believe it's c. the trait for large beaks will be passed on to future generations through natural selection.

since eventually smaller beaks would have to find another source of food or even eventually just die out from the lack of food.