Read the dialogue and answer the question.
Efe: I am going to the science fair tomorrow.
Selin: What are you going to present?
Efe: My project on solar energy. I built a small solar panel and tested it.
Selin: That sounds interesting. What did you find?
Efe: The panel produced enough energy to light a small bulb.
What did Efe do in his project?
A)He only read about solar panels.
B)He built and tested a solar panel.
C)He wrote a report about solar energy.
D)He bought a solar panel.