The author is talking about______.

A．A perception of any action, or institutional structure.
B．Age or any assignment of roles in society purely based on age.
C．Respect to others maintained to stereotype other people.
D．Respect to self maintained to affect one's self-concept.

A．Most of the research made on ageism is empirical and incomplete.
B．The inconstant nature of the age classification makes it different from other "isms".
C．This discrepancy referred to in the last paragraph is only concerned with methods.
D．The self concept may vary with the change in the ageist attitudes.