Answer: B. Bullying
Explanation: bullying is the act of trying to physically, mentally or emotionally harm or intimidate someone who looks less likely to retaliate i.e vulnerable. This is usually caused by social imbalance, where a particular group or individual feels superior to their victim. The mathematics professor was a victim of bullying as the group of managers felt he was vulnerable and less likely to retaliate. Bullying can have alot of resultant effects and being emotionally drained is just one of them which the mathematics professor was going through.