nautilids are marine mollusks that begin growing their shells before emerging from their eggs and continue…

nautilids are marine mollusks that begin growing their shells before emerging from their eggs and continue to add shell segments throughout their lifetimes. the walls between their shells chambers are called septa, and the concentration of the isotope oxygen - 18 they contain exactly reflects the isotopes concentration in the water at the depth at which the septa formed. paleontologist amane tajika and colleagues examined each of the septa in two nautilid shells; finding that sample f13 had a higher concentration of the isotope than sample m03 did, the researchers concluded that f13 must have formed at a significantly lower temperature than m03 did. which finding, if true, would most directly support the researchers conclusion? a) as the concentration of oxygen - 18 in water decreases, water temperature decreases and nautilid shell growth slows. b) as water depth increases, both the concentration of oxygen - 18 and the water temperature decrease. c) as water depth increases, the concentration of oxygen - 18 increases and water temperature decreases. d) as water temperature increases, nautilids are able to concentrate more oxygen - 18 into their shells.

nautilids are marine mollusks that begin growing their shells before emerging from their eggs and continue to add shell segments throughout their lifetimes. the walls between their shells chambers are called septa, and the concentration of the isotope oxygen - 18 they contain exactly reflects the isotopes concentration in the water at the depth at which the septa formed. paleontologist amane tajika and colleagues examined each of the septa in two nautilid shells; finding that sample f13 had a higher concentration of the isotope than sample m03 did, the researchers concluded that f13 must have formed at a significantly lower temperature than m03 did. which finding, if true, would most directly support the researchers conclusion? a) as the concentration of oxygen - 18 in water decreases, water temperature decreases and nautilid shell growth slows. b) as water depth increases, both the concentration of oxygen - 18 and the water temperature decrease. c) as water depth increases, the concentration of oxygen - 18 increases and water temperature decreases. d) as water temperature increases, nautilids are able to concentrate more oxygen - 18 into their shells.

Answer

Brief Explanations:

The researchers' conclusion is based on the relationship between oxygen - 18 isotope concentration in nautilid shell septa and water conditions. If as water depth increases, oxygen - 18 concentration increases and water temperature decreases (Option C), it supports the idea that different water conditions can lead to different oxygen - 18 concentrations in the shells, which is in line with the researchers' reasoning about the samples F13 and M03 having different oxygen - 18 concentrations and temperatures.

Answer:

C. As water depth increases, the concentration of oxygen - 18 increases and water temperature decreases.