Which of the following are the possible causes of pilot pollution? (Multiple Choice)

Which of the following are the possible causes of pilot pollution? (Multiple Choice)
A . The layout of the cell is unreasonable
B. Base station location or antenna hanging height is too high
C. There is a GSM 1800M interference source around the base station
D. Antenna azimuth or downtilt setting is unreasonable
E. The pilot power setting is unreasonable

Answer: ABDE