When may a scientific theory be revised?

-never, once it has been published

-when a single experiment's data goes against it

-when a new hypothesis provides a better explanation

-after a large amount of data refutes it

The answer to this question would be: - after a large amount of data refutes it

Scientific theory always got revised, so the first option definitely out. Theory must be backed up by much data, so to revise it you also need a large amount of data, not only one experiment. One experiment data won't prove much since the experiment method might be wrong. Hypothesis won't revise a theory, they are a different being