the following is a student draft. it may contain errors.

one example of scientists working to make people's lives better is through their development of underwater greenhouses, a sustainable method for producing food. one underwater greenhouse, a set of pods anchored to the sea floor just outside the coast of italy's liguria region, is called nemo's garden.
nemo's garden was developed in 2012 by a company called the ocean reef group. through their experiments at nemo's garden, the group was able to learn that plants grow faster underwater. this discovery led the scientists to conclude that underwater greenhouses could be one way to ensure that countries experiencing drought or other conditions that impact farming would still have access to healthy food.
the pods found in nemo's garden look similar to something one would see in a science fiction movie. the pods are various sizes and float at different depths, which keeps the plants safe. the dome at the top of each pod allows sunlight to enter, which keeps the plants warm despite the fact that the surrounding water is much cooler.
the crops in nemo's garden must remain hydrated to grow. additionally, the plants must be maintained by a special group of divers and monitored twenty-four hours a day through the use of cameras and sensors.
while underwater greenhouses are not without problems—mainly due to leaking and decay—scientists are hopeful about their potential future uses.

19
select the correct answer.
read the sentence from the draft.

the pods are various sizes and float at different depths, which keeps the plants safe.

what is the best way to revise the sentence for clarity?

a.
the pods, made from a hard plastic called acrylic, can hold approximately 2000 liters of air; they float at depths 20-30 feet below the ocean's surface, which keeps the plants safe from harmful weather conditions above.
b.
pods can hold thousands of liters of air and can be made into many sizes and shapes by using tough, acrylic plastic; the air and acrylic allow the pods to float several feet below the ocean's surface, so as not to become damaged from bad weather.
c.
acrylic is used to make the greenhouse pods, because it is strong and can be fashioned into a variety of sizes and shapes; acrylic floats better than other materials, so it is ideal for keeping plants safe from hazardous weather conditions.
d.
the acrylic pods are created in many sizes, including big, small, and medium, as well as other sizes needed by the scientists; they are connected to the seafloor by chains and float some distance below the surface, so the plants are