bacteria survive in the harsh environment of the stomach because it is able to neutralize the gastric acids and live in the mucosal stomach lining, safe from the host's immune responses.

Archaebacteria



Explanation:

It is the only bacteria able to survive harsh environments.

(P.S. why did you delete my 1st response?)

The correct answer for this question is that a statement that can be proven by observation or measurement is known as a fact. The other possible answers here simply refer to idea that different individuals can place value on, but that are not necessarily known to be true.