C) Why are vaccines important in preventing infections of more dangerous viruses?

Vaccines are important in order to prevent infections of more dangerous viruses because with the help of vaccine body makes antibodies which helps in protecting the body against viruses.

Explanation:

There is no medicine present in vaccines. Vaccine contains dead virus which is injected in the body. When the immune system detect these viruses, they make antibodies that are effective in controlling the virus. When these viruses attack again, the body is prepared for it.

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.

he forelimbs below belong to four species that descended in a direct line from the ancestral mammal shown above. of the four descendants shown, which species most likely appeared earliest in evolutionary history?