Early submersibles were dangerous and could remain underwater for only a few hours at a time. How did Robert Ballard solve this problem? * 1 point

A. He joined millionaire Jack Grimm’s team in its quest to find the Titanic.

B. He borrowed sonar equipment from the U. S. Navy.

C. He read survivors’ stories about the night the Titanic sank.

D. He designed a remote-controlled submersible.