Question

after a volcanic eruption spilled lava into north pacific ocean waters, a dramatic increase of diatoms (a kind of phytoplankton) near the surface occurred. scientists assumed the diatoms were thriving on nutrients such as phosphate from the lava, but analysis showed these nutrients werent present near the surface in forms diatoms can consume. however, there was an abundance of usable nitrate, a nutrient usually found in much deeper water and almost never found in lava. microbial oceanographer sonya dyhrman and colleagues believe that as the lava plunged nearly 300 meters to the seafloor it dislodged pockets of this nutrient, releasing it to float upward, given that ____________. which statement most effectively uses data from the table to complete the sentence? choose 1 answer: a at 5 - 45 meters below the surface, the average concentration of phosphate was about the same in the seawater of the lava - affected area as in the seawater outside of the lava - affected area. b for both depth ranges measured, the average concentrations of nitrate were substantially higher in the seawater of the lava - affected area than in the seawater outside the lava - affected area. c for both depth ranges measured in the seawater in the lava - affected area, the average concentrations of nitrate were substantially higher than the average concentrations of phosphate. d in the seawater outside of the lava - affected area, there was little change in the average concentration of nitrate from 75 - 125 meters below the surface to 5 - 45 meters below the surface.

Explanation:

Step1: Analyze the context

The passage is about diatoms thriving after a volcanic - eruption and the role of nutrients. It mentions that nitrate is a key nutrient and the scientists' hypothesis about its release.

Step2: Evaluate each option

Option A is about phosphate, not nitrate as per the context, so it's incorrect. Option B says nitrate concentrations were higher outside the lava - affected area, which goes against the idea that the lava might have released nutrients for diatoms. Option C correctly relates to the idea that nitrate concentrations in the lava - affected area are higher, which supports the hypothesis that the lava released nitrate for the diatoms. Option D is about phosphate change and not relevant to the nitrate - based hypothesis.

Answer:

C