In Which of the Following Situations Could an Employee's Performance

In which of the following situations could an employee's performance issues be attributed to external factors?

A) Nellie Riles has been called by her supervisor for a disciplinary meeting over her tendency to waste time using the Internet at work.
B) Malcolm Barnes has been assigned to three different supervisors in quick succession in the three months he has spent in the company because of conflicts at work.
C) Carl Torres takes frequent breaks to receive phone calls at work and this results in his failing to meet daily targets and delaying work schedules.
D) Jeremy Jones was a social drinker but after joining the sales division of a highly competitive firm, he began drinking after work with his colleagues every day, which has affected his performance adversely.
E) Aaron Wood has been requesting his supervisor repeatedly to replace the obsolete machinery on their production floor, but no action has been taken yet.