Bro please help asap TwT

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 about
transformers for my electronics
project.
B. I needed a reference book for my
electronics project; it had to be a
book on transformers.
C. I needed a reference book for my
electronics project about
transformers.