The first junction on transistor consisting of two back to back P-N Junction was invented in 1951 by william schockley.Later New Bipolar Junction Transistor(BJT) were invented.Transistor has three doped regions forming two P-N junction between them.There are two types of transistors (i) P-N-P and (ii) N-P-N .Each transistor has three segments (i) Emitter (ii) Base (iii) Collector. The size and level of doping is different of all three segments.For connecting in the circuit three terminals of a transistors are available - emitter , base and collector and it can be connected in three configuration Common Emitter(CE) , Common Base(CB) and Common Collector(CC).the transistor can be used as a device application depending on configuration used,the biasing done to the segments and operate in the region namely cut off , Active and Saturation.It can work as an amplifier , a switch and an oscillator too.Based on transistor knowledge give answer.

Which of the following is an n-p-n transistor:

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