Let us define each of these epochs.
1. Eocene - covers 56 to 33.9 million years ago after the extinction of dinosaurs.
2. Miocene - covers 23.3 to 5.3 million years ago where countries had warmer global climates
3. Paleocene - covers 66 to 56 million years ago where the forests were very dense and there was ecological evolutions
4. Pliocene - covers 5.3 to 1.8 million years ago when grasslands were abundant
From the choices, the answer would be Pliocene. This is the shortest epoch of the Cenozoic era.
