What's your ethnicity?

Those options are not different ethnicities, they are different geographical locations.

Asians are not a homogeneous population. East Asians like Chinese, Japanese, and Koreans are genetically dissimilar to Southeast Asians (Hmong, Thai, Khmer, Malay, etc.) and "Asian" Indians are in fact a Caucasoid cline, like Middle Easterners.

Africans... most people would assume you mean Sub-Saharan, or Black African, but North Africa is also a part of Africa, though it is populated by Arabs.

You did not state that by 'American' you meant exclusively North American, yet you included South American as a seperate option - though there is almost no difference in ethnicity between indigenous North Americans and indigenous South Americans.

 

I'm just plain old boring white. Northern/Western European mostly.