HEL PLEAS Although scholars debate the exact numbers, in Alvin Josephy's estimate, the Indian population fell from between fifteen and twenty million when the white man first arrived to a fraction of that 150 years later. Undoubtedly the Indians perished in great numbers. Yet although European enslavement of Indians and the Spanish forced labor system extracted a heavy toll in lives, the vast majority of Indian casualties occurred not as a result of hard labor or deliberate destruction but because of contagious diseases that the Europeans transmitted to the Indians. The spread of infection and unhealthy patterns of behavior was also reciprocal. From the Indians the Europeans contracted syphilis. The Indians also taught the white man about tobacco and cocaine, which would extract an incalculable human toll over the next several centuries. The Europeans, for their part, gave the Indians measles and smallpox. (Recent research has shown that tuberculosis predated the European arrival in the new world.) Since the Indians had not developed any resistance or immunity to these unfamiliar ailments, they perished in catastrophic numbers.
-- From ‘The Crimes of Christopher Columbus’ by Dinesh D'Souza, 1995

The author of this article believes that the Native American population declined greatly mostly because of

A.
enslavement, mistreatment, and hard labor.

B.
lack of immunity to some diseases.

C.
violent conflict.

D.
unhealthy patterns of behavior.