Which is the best choice for showing how to join the sentences? swimming races are won by inches. the new suits can make a difference

I would say D) Because swimming races are won by inches, the new suits can make a difference. It's joining a statement and a reason for the statement.

that his long years of service outweigh any faults he may have had.

he wanted to be remembered for the good things he did, one of those being when he gave up office so others would follow suit, but george washington wasn’t a man who thought he was perfect, he knew he made mistakes. he was a very talented soldier with a natural gift of tactic.