You would generally not be able to recover fossils from volcanic or plutonic rock, so looking around in an area on active volcanic islands would yield nothing.
You always want to look in the layers of sedimentary rock for fossils. The Grand Canyon would be a great place to see these layers as well as a shallow ocean because you may find the remains of prehistoric shark teeth or bones protruding through the surface of the sand.
The answer is Active volcanic islands.
If this is a question in which you can choose more than one answer it may be smart to also choose a shallow ocean as well. This is because it is difficult to get the tools and materials necessary down in the water and would be difficult to get deep enough underneath sand to start digging into actual fossil bearing rock.
So in that case, the answer would then be both Active volcanic islands and A shallow ocean.
