People do not have an absolute threshold for happiness. Rather, feeling happy or unhappy is the result of comparing the current state with a reference point. If our current status is above that point, we feel happy. If it is below that point, we feel unhappy. How is that reference point derived?

The reference point of happiness is derived from personal perceptions.

Explanation:

Perception is a product of the individual's learning, memory, expectation, and attention to sensory signals.  Individual perceptions are shaped by many factors.  One factor relates to the fact that individuals have some differences in how they assess their emotional states.  Some individuals focus on themselves, while others focus on other people.  The loci of focus affect how they perceive their happiness.  Another factor is the way individuals process information.  Some process information quickly while other people take time to think and process the information about their states of happiness.  The depth of attribution also differs from one person to another.  This suggests that while somebody may be considered to be unhappy, the same individual may be enjoying his or her life without qualms.

answer:

i believe the answer is d).

explanation:

i think this is because you are tearing apart the muscle, and then when you eat, the muscle re-heals, making itself even stronger.

edit: i put b) before but i meant to put d). sorry for the incorrect answer.

answer:

it is much easier to find