Compensation

A semiconductor has been doped with both donors and acceptors, making it compensated.  Compensation occurs when ND and NA are approximately equal, but the magnitude of the difference between them is less than  ni.  In this situation the dopants tend to cancel each other out and the semiconductor almost behaves intrinsically.  The band diagrams below are snapshots of the doped semiconductor at different temperatures.  Do you know what we mean by snapshots?

Which of the band diagrams below is at:
(Choose a temperature for each situation.)

0K 50K 300K 500K NEVER
 a.) 
0K 50K 300K 500K NEVER
 b.)
0K 50K 300K 500K NEVER
 c.) 
0K 50K 300K 500K NEVER
 d.)
0K 50K 300K 500K NEVER
 e.) 
0K 50K 300K 500K NEVER
 f.) 

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