Ornithology is the
A. Study of bones B. Study of birds C. Study of smells
D. None of these
Which of the following is used in pencils?
A. Graphite B. Silicon C. Charcoal
Why isnâ€™t electricity considered a primary energy source?
A. It is not as powerful as other energy sources. B. It is not the most common energy source. C. It was not the first energy source discovered.
D. It is produced by another energy source.