参考答案

正确答案：C
解析：事实细节题。在文章第四段中作者直接地告诉人们：Byrd even affirms that it is probably the most healthy climate in the world, for the intense cold of thousands of years has sterilized this continent, and rendered it absolutely germfree, with the consequences that ordinary and extraordinary sicknesses and diseases from which man suffers in other zones with different climates are here utterly unknown.