Answer: Glass escalator
Explanation:
Glass escalator is the concept that describes about promotion or advancement of men to a higher-level position in a female dominated working sector.In this field, men are chosen for the advanced role over women easily for advantages.This concept can be seen in professions like nursing, teaching field, social work etc.
According to the question, Gerald is promoted to the principal post over Zoya even though both had equal qualification describes glass escalator concept.Gerald is given advancement as he is a man in women-dominated field of schooling and education.