'People have seen ghosts for centuries, and no one has proved that ghosts do not exist. Therefore, ghosts are real.' This indicates which fallacy?

The claim that ghosts are real rests on no one having proved that they are not.

Absence of a disproof is treated as if it were positive proof.

Long-standing sightings are hearsay, not evidence of existence.

Lack of evidence against a claim never establishes the claim as true.

Concluding truth from an unproven falsity is the argument from ignorance, ad ignorantiam.