The answer is B. When diatoms die and fall off the ocean column to the ocean floor, they become part of sediments over time. When they are mined and exposed, they turn to a diatomite. Diatomaceous earth is significant as a pest repellant because of its hygroscopic property and has very abrasive particle hence it absorbs the water-protective fats and oils from the outermost layer of insects.
DNA has a double helix structure. The outer edges are formed by alternating deoxyribose sugar molecules and phosphate groups. The two strands run in opposite directions one going in a 3 to 5 the other going in a 5 to 3.
