The process of regurgitation is when an animal spits it's food back up its esophagus wilfully. Muscles in the animals stomach and throat work together to force food back up and out if the body. Long story short, it's like voulantary vomitting.
Hope this helps : )
You need to read the introduction like this
Answer: C. The sign of the enthalpy of the reaction reverses.
Explanation: Enthalpy of a reaction is the net heat absorbed or released during a chemical reaction.It is represented by
. It is negative for exothermic reactions in which heat is released and is positive for endothermic reactions in which heat is absorbed.
When a chemical reaction is reversed the heat of the reaction changes its sign.

The decomposition of calcium carbonate is an endothermic reaction as heat is required to break the bonds and thus energy is absorbed.

When the reaction is reversed, the reaction becomes exothermic as now bonds are getting formed and energy is released.
Hi you’ve only provided one of the options but I don’t know if this will help. The cell membrane is a Thin flexible barristers that surround all cells. Selectively permeable is some substance to pass across while others cannot. Hopefully that can give you give an idea.