Concept:
Fossils are the preserved remains or traces of ancient plants and animals.
They are usually found in sedimentary rocks because these rocks are formed by the gradual deposition of sediments, which can bury and preserve organisms.
Step 1: Consider different rock types.
• Igneous rocks form from molten magma and usually destroy fossils.
• Metamorphic rocks undergo heat and pressure, which generally destroy fossils.
• Sedimentary rocks form by deposition and preserve fossils.
Step 2: Identify the correct rock type.
Therefore,
\[
\boxed{\text{Fossils are generally found in sedimentary rocks}.}
\]
Hence, the correct option is
\[
\boxed{(D)\;\text{Sedimentary Rocks}.}
\]