Which region has the largest number if the 10 most populous countries within its boundaries

The South Asian region has the "largest number" of the "10 most populous countries" within its boundaries.

Explanation:

Out of the 20 most populous countries in the world, 9 are hosted by South Asia alone. These countries are namely China, India, Indonesia, Pakistan, Bangladesh, Japan, The Philippines, Vietnam, and Thailand. China being at the top of the list makes about 18.59% of the total world population. It is followed by India which makes about 17.71% of the total world population. A little above 25% of the world population is constituted by South Asia alone.

You not be doing this in a quiz. if you actually studied your work you would know the answer. the answer though is that they would use gdp per capita because it measures a smaller portion (person). this could show individual growth per person in the country.