"돼요" is correct, and it's short for "되어요"^^/ If you just remember that "돼" is the contraction of "되어", you won't be wrong.^^/ Here are some more. 되다(the base form) / 돼다(X) 되고(O) / 돼고(X) = 되어고??(doesn't make sense) 되어(O) / 돼어(X) = 되어어??(doesn't make sense) 되니(O) / 돼니(X) = 되어니??(doesn't make sense) 될 것이다(O) / 됄 것이다(X) 되서(X) / 돼서(O) = 되어서(makes sense) 되야(X) / 돼야(O) = 되어야(makes sense) 됬다(X) / 됐다(O) = 되었다 \^o^/

the correct one is 돼요 = 되어요 from 되다 (base form). Inflection of 되다= 1. 돼(pre)/ 됐어(pa)/ 될 거야(fu): informal low (speaking to your friend or same age/younger age people) 2. 돼요(pre)/ 됐어요(pa)/ 될 거예요(fu): informal high (speaking to your friend more formal) 3. 된다: to write a report or newspaper 4. 됩니다(pre)/ 됐습니다(pa)/ 됄 겁니다(fu): formal 5. 되세요(pre)/ 되셨어요(pa): informal high (speaking to older age people and need a honorific mark) 6. 되십시오: propositive informal highest 7. 되자: propositive informal low 8. 됩시다: propositive informal high 9. 되면: if... 10. 되고: and... 11. 됨: nominal ing