Which of the following statements correctly describes a surjective (onto) function f:A→B?
a) No two distinct elements of the domain map to the same element of the co-domain.
b) Every element of the domain maps to a unique element in the co-domain.
c) Every element of the co-domain has at least one pre-image in the domain.
d) The image (range) of the function is a proper subset of the co-domain.