illegal use of ergogenic substances
I'm pretty sure the answer is D. bile.
Answer:
They are the most effective way of inserting medicine.
If they weren't needles, they would definitely be used more.
Explanation:
Many times vaccines need to be administrated into muscles and strong tissue, so they need a needle to get all the way through. Other ways of giving vaccines are proved to be less potent and do not work as well.
Research also shows that 24% of parents fear needles and 63% of children fear needles.
