The quote by Carl Sagan: "Absence of evidence is not evidence of absence." This quote implies that

(a) If we cannot find evidence that there is discrimination, then discrimination doesn't exist.

(b) If we cannot find evidence that discrimination in sports exist, doesn't mean that discrimination doesn't exist.

(c) If we find evidence of discrimination, the discrimination exist.

(d) If we find evidence of discrimination, then it is still possible that discrimination doesn't exist.