Han asks you, "do people become happier with age?" according to the text, the most reasonable answer is

It is impossible to tell because the results of studies are contradictory.

Some people get happier with age because they manage to achieve what they want in life and tend to seek happiness based on a relationship with other people rather than shallow or materialistic things.

Some people grow miserable with age because they felt that they wasted their life away and resent themselves for it.