Which choice best states the main idea of the text? | Verbal SAT Question

In environments ranging from shallow tidal areas to the deep ocean, single-celled marine foraminifera have been found to contain phosphate at concentrations many times greater than those in the surrounding water. Notably, though, species from oxygen-rich environments like the Mid-Atlantic Ridge show lower phosphate concentrations than species from oxygen-poor areas. Scientists have thus suggested that especially high internal phosphate concentrations enable foraminifera to offset the effects of low oxygen.

Which choice best states the main idea of the text?

There is a correlation between habitat depth and phosphate concentration in marine foraminifera, with deeper-dwelling species generally maintaining higher internal concentrations.

While marine foraminifera in general have high phosphate concentrations, those concentrations tend to vary by species’ habitat, possibly reflecting adaptations to different levels of oxygen.

Marine foraminifera maintain similar phosphate concentrations across different ocean environments, suggesting that while this trait plays a role in offsetting low oxygen levels, that is not its only function.

Marine foraminifera counterbalance the effects of reduced oxygen levels by storing phosphate at high concentrations, matching or in some cases even slightly exceeding the phosphate concentration in the surrounding seawater.