Final answer:
Pain perception differs among individuals due to genetic variations and hormonal regulation, contributing to differences in nerve receptor density and hormonal pain modulation.
Step-by-step explanation:
The perception of pain varies among individuals due to several factors, and the answer to why not everyone experiences pain the same way is d) Both b and c, which includes genetic variations and differences in hormonal regulation. These factors contribute to individual differences in nervous system responses to painful stimuli. Genetic factors can influence the presence or density of nerve receptors, as well as the structure and function of the nervous system itself. Hormonal differences, which can also be due to genetic differences and can vary between sexes, play a role in modulating pain sensation and tolerance.
Some individuals, for example, may have a higher density of sensory receptors, leading to more intense pain sensations, while others might have higher levels of certain hormones that help to mitigate pain. The example of congenital insensitivity to pain also highlights how genetic disorders can lead to an absence of pain sensation entirely, which can result in unintentional injuries and a lower life expectancy.