题目选项分析

Both the caribou and the reindeer belong to the species Rangifer tarandus, but after 7,000 years of domestication in Eurasia, reindeer have developed a tendency to circle in tight groups, while caribou tend to spread far and wide.

Both the caribou and the reindeer are the same species, Rangifer tarandus, but about 7,000 years of domestication in Eurasia have developed reindeer's tendency to circle in tight groups, while the tendency is for caribou to spread far and wide.