Which of the following was Spain's primary motivation
for colonizing the Americas?

In addition to the quest for gold, however, Spain sought to spread Christianity. To this end, missions were founded in present-day Florida, Texas, New Mexico, Arizona, and California—indeed, anywhere the Spaniards had influence. The main goal of these missions was to convert Native Americans to Christianity.

Explanation:

the causes of the dust bowls were severe droughts,   lands became dry and hard, temperature was higher than usual, hot and dry conditions killed crops, high winds. because of those factors, the winds kicked up dry soil and created clouds of dust.

warfare was the primary means of cultural transmission in both regions.