Manganese nodules are what type of deposits

Well manganese nodules are the deposits that have really very slow forming process and they are mostly confined or most probably found in abyssal zones (deep sea level). They are ...

The answer is D) chemical. As manganese nodules are formed by chemical precipitation of metallic deposits around a nucleus in a concentric manner.

The manganese nodules consist of concentrically banded zones of micro-layers around a nucleus. They form by chemical process of metal precipitation either from the ambient seawater...