<em>"Historically, it has been proven that the wright brothers spent all their money on building and testing their airplane. Although it was a genius idea, their attempt wasn't very successful. The Wright Brothers then lost all their wealth, and could not afford to buy paint..."</em>
I dont really understand the word <span>efficacy
but the others dont seem to make sense to me so i would say D unless i just am misunderstanding a key concept </span>
