Question

Which two of these characteristics are common to epics and ballads? Both originated from the oral poetic tradition. Both revolve around the exploits of a central hero. Both use iambic pentameter and a simple rhyme scheme. Both contain the elements of a narrative. Both are exclusively focused on mythological stories.

Answer 1

Ballads and epics are forms of verse which are often narrative. Ballads are dancing songs. Traditional ballads emphasize central dramatic event, and recount comic or heroic stories. Epics on the  other hand are lengthy narrative poems concerning serious subjects like details of heroic stories or deeds and events important to a nation or culture.
Both contains the elements of a narrative.

Answer 2

Both contain the elements of a narrative. Both originated from the oral poetic tradition.

One famous epic is the Epic of Gilgamesh. It is not written in iambic pentameter and is not solely focused on mythological stories. These two options are then eliminated automatically. It does revolve around a central hero, originate from the oral poetic tradition, and contain the elements of a narrative.  A famous ballad is Poe's Annabel Lee. It is not written in iambic pentameter, focused on mythological stories, or revolve around the exploits of a central hero. The only thing is has in common with Gilgamesh is originating from poetic tradition and containing elements of a narrative.