Scientists used to exploreon the surface of the ocean. Now they are exploring below the surface, too. They want to know about ocean water and the plant and animal life deep in the ocean. In 1934 the scientist William Beebe dived 3 000 feet below the surface in a hollow steel ball. In 1935 August Piccard dived 10330 feet. In 1960 his son Jean dived to a depth of 35 800 feet. All these early dives were deep. But the divers could not stay down for very long. They had to come back up to the surface after a few seconds. Scientists needed to stay down longer to study life below surface. Gradually they succeeded. Cousteau, a Frenchman, was able to keep men down to a depth of 90 feet for a week. Now scientists are developing even better equipment. With this new equipment,men can stay below the surface for days or even weeks. In 1962 Cousteau set up a research station 35 feet below the surface. Then,in 1964,he set up another station on the ocean floor of the Red Sea. This was the first undersea station to operate without help from the surface. Many countries are now studying undersea living. The former Soviet Union has an undersea laboratory in the Crimean Sea. The United States has a laboratory 50 feet down on the ocean floor off the Virgin Islands. In 1970 five men lived there for two weeks. Then a team of five women scientists stayed in the laboratory. Next came other teams of men. All were there to explore the ocean depths and to make plans for the use of its resources. Scientists hope to find enough mineral,vegetable,and animal wealth there to provide food for the entire world. In order to  _   ,scientists are exploring below the surface of the ocean.
know about the ocean water deep in the ocean stay down longer to study life of the plant and animal below the surface know about the plant and animal life deep in the ocean both A and C
Question: Scientists used to exploreon the surface of the ocean. Now they are exploring below the surface, too. They want to know about ocean water and the plant and animal life deep in the ocean. In 1934 the scientist William Beebe dived 3 000 feet below the surface in a hollow steel ball. In 1935 August Piccard dived 10330 feet. In 1960 his son Jean dived to a depth of 35 800 feet. All these early dives were deep. But the divers could not stay down for very long. They had to come back up to the surface after a few seconds. Scientists needed to stay down longer to study life below surface. Gradually they succeeded. Cousteau, a Frenchman, was able to keep men down to a depth of 90 feet for a week. Now scientists are developing even better equipment. With this new equipment,men can stay below the surface for days or even weeks. In 1962 Cousteau set up a research station 35 feet below the surface. Then,in 1964,he set up another station on the ocean floor of the Red Sea. This was the first undersea station to operate without help from the surface. Many countries are now studying undersea living. The former Soviet Union has an undersea laboratory in the Crimean Sea. The United States has a laboratory 50 feet down on the ocean floor off the Virgin Islands. In 1970 five men lived there for two weeks. Then a team of five women scientists stayed in the laboratory. Next came other teams of men. All were there to explore the ocean depths and to make plans for the use of its resources. Scientists hope to find enough mineral,vegetable,and animal wealth there to provide food for the entire world. In order to  _   ,scientists are exploring below the surface of the ocean.
A. know about the ocean water deep in the ocean
B. stay down longer to study life of the plant and animal below the surface
C. know about the plant and animal life deep in the ocean
D. both A and C
Answer: