What is the best way to combine these sentences using a prepositional phrase? (Be sure to keep the meaning of the original sentences.)
I needed a reference book for my electronics project. It had to be a book on the subject of transformers.
A.) I needed a reference book for my electronics project about transformers.
B.) I needed a reference book about transformers for my electronics project.
C.) My electronics project had to be a book on transformers.