The Following Questions Refer to the Excerpt Below

The following questions refer to the excerpt below.
"The late sixteenth and early seventeenth century were the time of what has been called the "little ice age" in the northern hemisphere,making it an inauspicious period for the founding of colonies. The little ice age is given various beginning and ending dates by historians of climate,most making it as broad as from the middle of the fifteenth to the middle of the nineteenth century. Because there was no unbroken run of cold winters and cool,wet summers,experts disagree about the outer limits of the period,but all agree that its greatest intensity was felt between 1550 and 1700. Severest winter cold and least summer warmth occurred in the 1590s,the first decade of the seventeenth century,the 1640s,and the last decade of the seventeenth century. The global mean temperature for the period was probably about one degree centigrade lower than in the relatively warm period from 1890 to 1950."
Historian Karen Ordahl Kuperman,
"The Puzzle of the American Climate in the Early Colonial Period"
-Which of the following historical concepts was most closely associated with the passage?

A) Spanish conquest was aided by epidemics that destroyed large segments of the population.
B) Indians in the western Great Plains were forced to develop mobile lifestyles because of changes in available natural resources.
C) African slaves were replaced by Indians as a source of forced labor.
D) New crops from Europe often flourished in the western hemisphere.