Which Statement Best Indicates How Inventors and Government Offices Were

Which statement best indicates how inventors and government offices were able to establish who was responsible for early developments in radio technology?

A) Patents clearly indicate who invented what piece of technology first.
B) Only Italians and Americans were interested in early broadcasting.
C) Inventors respected other inventors out of a sense of professional courtesy.
D) The early days of radio were heavily regulated, and therefore clearly documented, by government officials.
E) Simultaneous and independent discoveries, along with competing claims for patents, often had inventors going to court over their inventions.