Many People Are Not Familiar with Electric Cars

Many people are not familiar with electric cars. By introducing the concept, Tesla, and BYD help to educate car buyers about electric cars. What externality is at work?

A) Positive externality from Tesla and BYD to consumers.
B) Positive externality from Tesla and BYD to other manufacturers of electric cars.
C) Negative externality from Tesla and BYD to consumers.
D) Negative externality from Tesla and BYD to all other car manufacturers.