Which of the following are true for gravity?

I do not know any of the answers so I would probably say; gravity is the force that holds objects on the surface of the earth.

Since there are no options given so we can simply define gravity and its constraints.

Gravity, also called gravitation, is a force that exists among all material objects in the universe. Gravity is an attractive force, so it pulls all objects together irrespective of their masses. But it is understood that the object with larger mass will attract the smaller one towards itself. And as the distance between two objects increases, the force of gravity between them decreases.

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.