Here's why:

* Biochemical rocks are formed from the accumulation and cementation of the remains of organisms. These remains can be shells, bones, coral, or even microscopic plankton. Because these rocks are made from once-living organisms, they are likely to contain fossils.

Let's look at the other options:

* Clastic sedimentary rocks are made from fragments of other rocks. While they might contain fossils if those fragments came from a rock that was originally biochemical, they are not inherently formed from organic remains.

* Chemical sedimentary rocks are formed by precipitation of minerals from water. These rocks are unlikely to contain fossils unless they were formed in a location where fossils were already present.

Therefore, biochemical rocks are the most likely type of rock to contain fossils.