Keep scrolling down for answers and more stats ...
1.
Has the largest population
3.
Has the greatest highest elevation of the four options
Sri Lanka: 2,524 m, Romania: 2,544 m, Yemen: 3,665 m, North Korea: 2,744 m
4.
Has the largest land area
5.
Its capital is Yaoundé
6.
Is NOT a monarchy (any kind of monarchy, not just absolute)
7.
Has hosted the Olympics
8.
Has the tallest average people (of both genders)
9.
Has the lowest external debt
Afghanistan:1.28 billion, Djibouti: 1.34 billion, Belize: 1.33 billion, Equatorial Guinea: 1.36 billion
10.
Most densely populated
11.
Most time zones (including territories)
12.
Has a lake called "Nipigon"
13.
Was NOT colonized by the British
14.
Has the most official languages
This answer surprised me so here's the source: https://en.wikipedia.org/wiki/List_of_countries_by_the_number_of_recognized_official_languages
15.
With the highest median age
Mauritania: 21.9, Papua New Guinea: 21.6, Ghana: 21.3 East Timor: 20.3