The stim ... can test the "limits of human capacities to live in space ... be typical of the average human- they need to be greater ... atypical of that of ordinary human beings.
... ;
> > So understanding human limits=/= ordinary humans?
> ... gap between astronauts and knowing human limits? (last sentence)
> ... on par with the average human
Also, for D it doesn't say anything about these two populations being very similar - which paragraph1 says. but I guess D is enough b/c it says interbreed - and as long as you interbreed you can't be the same species ?