Answer:
D
Explanation:
everything compared to the sun is small
Answer: The answer is (4), centuries
Explanation:
Answer:
The safety and effectiveness of vaccines are under constant study. Because vaccines are designed to be given routinely during well-child care visits, they must be extraordinarily safe. Safety testing begins as soon as a new vaccine is contemplated, continues until it is licensed, and is monitored indefinitely after licensure.
Explanation:
