The Following Questions Refer to the Description and Table 28

The following questions refer to the description and Table 28.1 below.
Diatoms are encased in Petri-plate-like cases (valves) made of translucent hydrated silica whose thickness can be varied. The material used to store excess calories can also be varied. At certain times, diatoms store excess calories in the form of the liquid polysaccharide, laminarin, and at other times, as oil. Below are data concerning the density (specific gravity) of various components of diatoms, and of their environment.
Table 28.1: Specific Gravities of Materials Relevant to Diatoms
$$\begin{array} { l l } \text { Material } & \text { Specific Gravity } ( \mathrm { kg } / / \mathrm { m }^{3} ) \\\text { Pure water } & 1000 \\\text { Seawater } & 1026 \\\text { Hydrated silica } & 2250 \\\text { Liquid laminarin } & 1500 \\\text { Diatom oil } & 910\end{array}$$
-Using dead diatoms to "pump" CO? to the seafloor is feasible only if dead diatoms sink quickly. Consequently, application of mineral fertilizers, such as iron, should be most effective at times when diatom

A) valves are thickest, and laminarin is being produced rather than oil.
B) valves are thickest, and oil is being produced rather than laminarin.
C) valves are thinnest, and laminarin is being produced rather than oil.
D) valves are thinnest, and oil is being produced rather than laminarin.