Which of the following is true about scientific knowledge? it is based on personal beliefs. it is always perfectly certain. it can change based on evidence. it is an opinion that never changes.

The correct answer is : It can change based on evidence.

Science uses specific methods in order to acquire knowledge about the world. One of the most important rules of science is that all knowledge (facts, theories etc.) can be tested to determine weather if it is certain. Therefore, if a part of the scientific knowledge turns out not to be true, this evidence causes a change in the scientific knowledge.
Therefore, we can say that scientific knowledge is always changing, improving, and aims to be unbiased and objective.

I’d have to say no because without oxygen in the water the fish would all be dead. so if you want to fish for dead fish, pick the ponds with the lowest oxygen concentrations.