What is the definition of a topological space?

a$)$ A set together with a collection of subsets satisfying certain axioms regarding containment and intersection.

b$)$ A space that can be continuously deformed into another space without tearing or gluing.

c$)$ A space that satisfies the axioms of Euclidean geometry.

d$)$ A space that can be represented as a finite$-$dimensional vector space.