Solved by a verified expert:Populations are said to be sympatric when _______.(A) two populations are physically isolated by natural barriers.(B) two populations live together and freely interbreed to produce sterile offspring.(C) two populations share the same environment but cannot interbreed.(D) two populations are isolated but occassionally come together to interbreed.Populations are said to be allopatric when ________.(A) they are physically isolated by natural barriers (B) they live together and breed freely to produce viable offspring (C) they are isolated but often come together for breeding (D) none of the above