To interpret the Human Development Index (HDI) of North America, Central America, and the Caribbean accurately, the most relevant factor to consider is:
Canada and the U.S. have significantly higher scores than the rest of the countries.
This is important because the high HDI scores of Canada and the U.S. can skew the overall average for the region, making it appear more developed than it may actually be when considering the lower HDI scores of other countries, particularly in Central America and the Caribbean.