Question

which of the following is not true about index fossils?
they are easily recognized and abundant
they are compared to other fossils around the world
the organisms tended to exist for short periods of time
index fossils are always trilobites

Explanation:

Index fossils are widely distributed, existed for a short time, abundant, and easily recognizable. They are used for relative dating by comparing with other fossils. While trilobites are index fossils (in Paleozoic), index fossils are not always trilobites. There are many other organisms like ammonites (Mesozoic) that serve as index fossils.

Answer:

Index fossils are always trilobites.