According to the textbook, why did diseases such as smallpox and measles produce epidemics that ravaged or completely wiped out native populations in the americas after contact with europeans in the late fifteenth century?

a. the native peoples lacked resistance to these diseases.
b. europeans refused to share their medicines with the native peoples.
c. europeans forced the native peoples to abandon their traditional medicines, which had kept the diseases largely at bay before contact.
d. europeans forced the native peoples to relocate to massive urban centers, where the bacteria easily spread.

Answer:

According to the textbook, the diseases such as smallpox and measles produce epidemics that ravaged or completely wiped out native populations in the Americas after contact with Europeans in the late fifteenth century because (A) The native Americans lacked the immune system to fight diseases like measles and smallpox.  

Explanation:

With the arrival of the Europeans in native America in the 15th century many diseases were brought. These diseases took the form of epidemics and almost wiped away the population of native Americans. This happened because the Americans had no contacts before with the European culture and lifestyle thus they didn't develop the necessary immune system internally to fight diseases like measles, smallpox, cholera etc. They also lacked the medicines to prevent or fight these diseases.