Charlie writes the steps shown to describe the use of a transistor in a closed circuit with flowing current. Using a Transistor to Amplify a Signal
1. Current (I1) flows from the base to the emitter.
2. An input causes a small increase in voltage across the base and emitter.
3. I1 increases a small amount.
4. Current (I2) flowing from the emitter to the collector changes a large amount.

Which change corrects the error in his steps?

Change the title to “Using a Transistor as a Switch.”
Change step 1 to say that no current flows in the transistor at the start.
Reverse the sizes of the changes in current in steps 3 and 4.
Reverse the direction of current in step 4.