Answer: A. manganese nodules.
Biogenous sediment is sediment that is obtained from materials produced by marine plants or animals such as teeth, bones, shells, coral reefs and others. It comes from the hard parts of these dead animals and plants. Calcium and silica are the main biogenous sediments. For example, calcium carbonate is chief ingredient of coral reef. Teeth, bones and shells are made up of calcium. Silica is the outer cell wall of diatoms and protozoa and they are also useful for making shells of marine organisms. Phosphorous is also the component of organic matter deposited by the dead organisms.
Therefore, manganese nodules is not the part of biogenic sediment.
