When a low density lipoprotein particle is taken up by the cell, the impact it will have on the regulation of de novo cholesterol synthesis will be HMG-CoA reductase being dephosphorylated.
HMG-CoA( 3-hydroxy-3-methyl-glutaryl-CoA reductase) is an enzyme which aids the synthesis of lipids. When the lipids are produced and taken up by the cells then the effect of the synthesis stops to avoid excess synthesis and to allow for the action of enzymes which will act ok them in the cells . This is why it leads to a dephosphorylation of the enzyme which stops the action.
Your answer is C lithosphere because the availability of phosphorus is different than that of carbon and nitrogen because it is found mostly at the lithosphere.
