Answer;
B. Water Chemistry
Step-by-step explanation;
-The Scientific ocean exploration began in the 19th century, using wooden sailing ships. At that time, explorers had none of the technological sophistication and tools available today.
-The Challenger expedition was the first expedition organized specifically to gather data on a wide range of ocean features, including ocean temperatures seawater chemistry, currents, marine life, and the geology of the seafloor.
-HMS Challenger used sails rather than the steam engine most of the time to allow for frequent stops when collecting data. The steam engine was used only during dredging operations to collect samples from the depths of the ocean floor.