Is a fox chasing after a rabbit, competition, predation, or symbiosis?

advantage of using stem cells in medical research:

1.       it provides medical benefits in the fields of therapeutic cloning and regenerative medicine.

2. it provides great potential for discovering treatments and cures to a variety of diseases including parkinson disease, spinal cord injuries, diabetes, alzheimer’s disease and many more.

3. limbs and organ could be grown in lab from stem cells and then used in transplant or treat illness.

as many times as you want

i believe it is "they are not used up by reactions" as the answer to your question, text me back if this is correct because i just learned this.