When must scientific theories be changed?

A. When one experiment shows a surprising result.

B. When a new government is elected.

C. When an old scientist dies

D. When new evidence is discovered

D because when new evidence is found other question will come up about it

Surprises are the reason there are new discoveries. We should clap our hands when we get a surprising result from an experiment.

Governments? What do they have to do with science unless they are funding the project. If they are not, science and governments do not really mix.

Well that has happened, but I don't think that's the answer.

D is your answer.