In Which of the Following Circumstances Does Brain Drain Occur

Multiple Choice

In which of the following circumstances does brain drain occur?

A) when jobs require long periods of intense concentration
B) when a person works in a job that doesn't require much thought or problem-solving ability
C) when highly skilled and educated people leave their home country in search of work abroad
D) when the best workers are promoted to managerial and administrative positions, leaving incompetent workers to do the other jobs