Answer:
The first line of defence (or outside defence system) includes physical and chemical barriers that are always ready and prepared to defend the body from infection. These include your skin, tears, mucus, cilia, stomach acid, urine flow, 'friendly' bacteria and white blood cells called neutrophils.
Explanation:
It's called chemical reaction.
(I'm not real sure)
Irreversible climate change and damage to marine and land life/humans.
c is the answer to your question
