The Answer is D. Hope this helps~
The answer in the space provided is experiments. It is because in order to produce causation or to likely have a cause of something in particular, they need to conduct experiments in which they will likely form new ideas and test this ideas to form something new that will cause and contribute to others and will be of gain of knowledge.
He<span> was born in Qufu, Zhou </span>Dynasty<span>, China in 551 BCE and </span>died<span> in 479 BCE. ... Kong Qui, better </span>known as Confucius<span>, was born in 551 B.C. </span>
