Final answer:
The statement about the danger of measles to Pacific Islanders in the nineteenth century due to exposure from traders and travelers is true. Infectious diseases like measles, brought by Europeans and U.S. visitors, led to significant loss of life among indigenous populations who lacked immunity.
Step-by-step explanation:
With traders and travelers crisscrossing the globe in the nineteenth century, the threat of measles to Pacific Islanders was particularly dangerous. The answer to this question is: a) True.
During the late nineteenth century, European and U.S. visitors brought infectious diseases to various regions, including the Pacific Islands. For instance, the introduction of measles to Fiji in 1875 resulted in a catastrophic death of approximately one-quarter of the population. This was due to the lack of immunity among the native population to diseases brought by foreign travelers.
Overall, diseases such as smallpox, measles, and influenza left by European explorers had a devastating impact on the indigenous populations of the Americas, with measles acting as not merely an irritant, as it was in Europe, but as a deadly pathogen to natives without prior exposure or immunity.