my caste is bce , bce are placed in bc but there is no option in which caste it should be placed

If you are saying you belong to BCE and it is under BC. Then please check the certificate which is provided by the authority. There is BC category in central list see the caste on the certificate if you have it will be written on it. If you don't have apply it, it will be written on it. And if it in state list and not in central list then you can apply that for only state and not central openings and exam.