Salivation by dog saw when food is given along with ringing of the bell is
In the given scenario, there is no prior learning process involved. When the dog sees food, salivation occurs. So it is an innate response. 
If the dog salivates when the bell is ringing, after a conditioning process, then it is conditioned reflex.
Conditioned reflex
Reinforcement
Habituation
Innate reflex