Why does taiwan have to enter athletes into the olympic games under the title "chinese taipei"?
a. because it was founded after world war ii
b. because all countries recognize it as a rogue state
c. because all countries recognize it as a sovereign state
d. because not all countries recognize it as a sovereign nation

The problem with Taiwan is that it has a dispute with China: both countries believe that they have the right to rule over both China and Taiwan! So China does not recognize Taiwan. And since China is very powerful, it can pressure other countries into not recognizing it either (most do, but  sometimes not completely).

the correct answer is:

d. because not all countries recognize it as a sovereign nation