How is it that Berkeley can claim to be an empiricst even while also saying that the world only exists inside our experience?

a. He is a rationalist, not an empiricist.
b. He does not claim the world exists only inside our sensory experience of it.
c. He says that the senses only show us sensory experience, never a world outside of the five senses.
d. He says that sensations are caused by a world outside the senses, but we just can't know what that world looks like.