Does a Turned creature have to take the Dash action?

A Turned creature (via a Cleric’s Turn Undead or an Oath of the Ancients Paladin’s Turn the Faithless) must

spend its turns trying to move as far away from you as it can… For its action, it can use only the Dash action or try to escape from an effect that keeps it from moving. (PHB p. 59 and 87)

Can a Turned creature simply avoid taking an action, or does it have to Dash (obstacles, terrain, etc. permitting)?