Which one of the following is correct in n-p-n transistor ?

CONCEPT:

Transistor:

• A junction transistor is formed by sandwiching a thin layer of P-type semiconductor between two N-type semiconductors or by sandwiching a thin layer of n-type semiconductor between two P-type semiconductors.
• NPN transistor: It is formed by sandwiching a thin layer of P-type semiconductor between two N-type semiconductors
  
• PNP transistor: It is formed by sandwiching a thin layer of N-type semiconductor between two P-type semiconductors.
  

Transistor consists of three main regions i.e. Emitter, Base, and Collector.

Emitter (E):

• It provides majority charge carriers by which current flows in the transistor.
• Therefore the emitter semiconductor is heavily doped.

Base (B):

• The based region is thin and lightly doped.
• It provides proper interaction between emitter and collector

Collector (C):

• The size of the collector region is larger than the two other regions and it is moderately doped.
• The main purpose of the collector is to collect majority charge carriers from the emitter. 
• From above it is clear that in transistors, the emitter is highly doped and the base is feebly doped.