The correct option is B uranium
Fossil fuels are made of buried organic material. Examples of fossil fuels are coal, oil. Coal is the result of buried plant material. Oil is thought to be the result of buried animal material. Just because you can dig something up that doesn't make it a fossil fuel. Uranium in fact is not "dug up" at all, it is uranium ore that is mined and subsequently converted into Uranium Oxide (U3O8/yellow cake). This is often refined into Uranium.
So, the correct option is option A.