The correct answer is D: Base-to-emitter voltage of approximately 0.6 volts to 0.7 volts. Which of the following indicates that a silicon NPN junction transistor is biased on is base-to-emitter voltage of approximately 0.6 volts to 0.7 volts. Silicon transistors turn on at about 0.6-0.7V base-emitter voltage. For amateur radio operators, this is important for transistor knowledge. Understanding this helps when biasing transistors.