Humans have observed and explored the oceans since ancient times.But it wasn't until the 19th century that the scientific study of oceans began.The first major scientific expedition,and the one that firmly established the field of oceanography,was the around-the-world voyage of H.M.S.  Challenger.Setting out from England in 1872,the Challenger spent almost three and a half years gathering a wealth of information about seawater,sea life,and the ocean floor.Major oceanographic expeditions since then have included the South Atlantic voyage of the German ship Meteor in 1926 and the Deep-Sea Drilling Project from 1968 to 1983.Many individuals also have played important roles in advancing our understanding of oceans,beginning with Matthew Fontaine Maury in the mid-1800s;his work on oceanography and navigation led to a uniform system of weather reporting at sea.Since Maury's time,oceanography has progressed rapidly.Early oceanographers had to contend themselves with tossing buckets overboard to see what they might haul in.Today's oceanographers are equipped with space images,supercomputer models,and deep-sea robots that can crawl along the seafloor.As they set goals for the future,some oceanographers even dream of doing research in permanently manned stations on the bottom of the oceans. How many expeditions are mentioned in this passage?
Four. Three. Five. Two.
Question: Humans have observed and explored the oceans since ancient times.But it wasn't until the 19th century that the scientific study of oceans began.The first major scientific expedition,and the one that firmly established the field of oceanography,was the around-the-world voyage of H.M.S.  Challenger.Setting out from England in 1872,the Challenger spent almost three and a half years gathering a wealth of information about seawater,sea life,and the ocean floor.Major oceanographic expeditions since then have included the South Atlantic voyage of the German ship Meteor in 1926 and the Deep-Sea Drilling Project from 1968 to 1983.Many individuals also have played important roles in advancing our understanding of oceans,beginning with Matthew Fontaine Maury in the mid-1800s;his work on oceanography and navigation led to a uniform system of weather reporting at sea.Since Maury's time,oceanography has progressed rapidly.Early oceanographers had to contend themselves with tossing buckets overboard to see what they might haul in.Today's oceanographers are equipped with space images,supercomputer models,and deep-sea robots that can crawl along the seafloor.As they set goals for the future,some oceanographers even dream of doing research in permanently manned stations on the bottom of the oceans. How many expeditions are mentioned in this passage?
A. Four.
B. Three.
C. Five.
D. Two.
Answer: