When marine organisms called phytoplankton photosynthesize, they absorb carbon dioxide dissolved in seawater, potentially causing a reduction in the concentration of atmospheric carbon dioxide, a gas that contributes to global warming. However, phytoplankton flourish only in surface waters where iron levels are sufficiently high. Martin, therefore, hypothesized that adding iron to iron-poor regions of the ocean could help alleviate global warming. While experiments subsequently confirmed that such a procedure increases phytoplankton growth, field tests have shown that such growth does not significantly lower atmospheric carbon dioxide. When phytoplankton utilize carbon dioxide for photosynthesis, the carbon becomes a building block for organic matter, but the carbon leaks back into the atmosphere when predators consume the phytoplankton and respire carbon dioxide.
- It can be inferred from the passage that Martin’s hypothesis includes which of the following elements?
A A correct understanding of how phytoplankton photosynthesis utilizes carbon dioxide
B A correct prediction about how the addition of iron to iron-poor waters would affect phytoplankton growth
C An incorrect prediction about how phytoplankton growth would affect the concentration of atmospheric carbon dioxide.
My question here is that the GRE inference question and answers pattern is broken here.
Answer A no direct evidence, it is here implicit not explicit.
I would like to hear from someone about the process to reach that answer A is correct.
