Rachel, a 35-year-old woman, is a manager at a leading software firm. Rachel is a dedicated and hardworking employee. Despite her work experience, she was overlooked for promotion twice. Instead, her male colleagues got promoted. She has finally decided to quit her job as she feels that she will not get the promotion that she deserves. In this scenario, which of the following has prevented Rachel from getting promoted?

-- Social loafing
-- Structural accommodation
-- A glass ceiling
-- An affirmative action plan