To be in the realm of science, a phenomena (event), must explain everything.

O be able to be disproven.

what people thought in the old days.

o be agreed upon by everyone.

B) be able to be disproven

Explanation:

Scientific investigations involve the use of scientific methods, which is a principled guideline for scientific observations. One of the steps of the scientific method includes formulating an hypothesis, which is a predictive statement about the possible solution to an observed problem. This hypothesis is FALSIFIABLE i.e it must via experimentation/testing be proven to be false.

This qualifies a happening or phenomena as SCIENTIFIC. It must be able to be repeatedly tested for the purpose of disproven or falsifying the hypothetical claim.

the answer is lactic acid from anaerobic respiration. the acid in lactic acid is what creates sore and burning muscles. if you think about how acid burns that will give you a clue for questions like this.