What would the options be if the topic was countries?
about ...
none
2**-1
2**0
2**1
2**2
2**3
2**4
2**5
2**6
2**7
2**8
...or more.
Depending on the definition of a country, there are in between 270 and 300 and some more on this planet. Actually visiting all of them may be hard to do.