Explanation

(a) In a junction transistor, both the electron and hole play role, hence they are called the
bi-polar devices or the bi-polar transistors and they are abbreviated as BJT is short form.
There are three parts in a transistor, namely emitter, base and collector. In the emitter part of the transistor the doping is more and it is less in collector part. The doping is very less in the base part. So, emitter current is actually the sum of base and collector current.
ie., $I_{E} = I_{B} + I_{C}$
Hence, maximum current flows in emitter region.