A $~n-p-n$ transistor conducts when:

• A

  both collector and emitter are positive with respect to the base
• Correct answer
  B

  collector is positive and emitter is negative with respect to the base
• C

  collector is positive and emitter is at same potential as the base
• D

  both collector and emitter are negative with respect to the base

Solution

In active region Emitter base $p-n$ function is in FB and base collector $p-n$ function is in RB.

Hence, the correct answer is option: 'B'.