Should science be governed by politics? Or should politics be governed by science?

Science is correct. It is based on the laws of nature, those are not arbitrary, and will hold true no matter what you want.

Politics is only limited to discussing the merit of doing something, or not doing something. But if science says that doing A will result in B, then trying to deny the consequence of action A is beyond foolish.

Nothing ruins science like politics.

Neither.

Politics should by INFORMED by science, but not "governed" by it.

And science should be as completely independent of politics as possible.

Politics should be governed by science; otherwise, you get a giant mess like Trump screwing up the pandemic response.

the latter case

politicians should heed what scientists have to say when creating their policies, science that would be dictated by politics would not be science it would be pseudo science, also known as junk science 

Science is a tool, and a human construct. It isn't an entity that can be owned or controlled. An event or incident cannot be bottled and resold. It's just a happening.

Ideally the two are completely separate

Like religion, politics and science should be independent of one another.  But try telling Democrats that.  They think science is some sort of dodge or hustle to be used for their political propaganda purposes.

The latter. If it's real science.