Explanation

Three axioms define a topology:

The empty set and the whole space must be open. 

The union of any collection of open sets must be open. 

The intersection of a finite number of open sets must be open. 

Why is option B incorrect?

While the intersection of a finite number of open sets is open, the intersection of an infinite number of open sets is not necessarily open.

This is a key distinction in the definition of a topology.