Fossils are primarily used for relative dating, helping to establish the age of rock layers based on the presence of specific fossil species. However, in the context of finding the absolute age of rocks, certain fossils can be more useful than others.
The best choice from your options would be:
if it existed for a limited period of time and in a wide area.
Fossils that were present for a short geological time but across a broad geographic area are typically referred to as "index fossils." These fossils are particularly valuable for dating because they provide a clear marker for a specific time frame. If a fossil is found in a rock layer, and that fossil is known to have existed during a specific and limited period, it can help geologists determine the absolute age of the rock layer in which it is found.