You have to select General Category when you are filling in the NEET application form. Use the link: https://ntaneet.nic.in/Ntaneet/Registration/NewReg.aspx . But when you are filling your State NEET registration form, please select OBC as your Category. This is because if your Caste doesn't fall in Central OBC list, you should select General Category as your Category but because 3B Category is State specific benefit, you need to select OBC as your Category while filling State NEET registration form for counselling.