Preparatory course utterly different from the JEE-Mains so you need to go ahead with one choice neither two nor three.

And the preparatory course will happen in the presence of the IIT professors once you’ve gone through the JOSAA choice filling in the endowed the time period and if you have the jee-Mains score then you can automatically get the NIT’s seats, if your rank will be fit for the closing and openings ranks at respective NIT’s.

If you get the NIT’s seat then blindly join there and start what you want really in lifesolely you can join preparatory for one yearand prepare well there and pass the examination which can conduct by the IIT-Professors after the preparatory course has been over and then take the IIT Admission and enjoy.

“Preparatory course is who did not qualify the JEE_Advanced and they can apply for the preparatory course for one year coaching at any IIT’s and IIT-Professors will teach to the students who’ve obtained the Preparatory course through the Josaa Online choice filling and perhaps this facility has been endowed to the SC/ST and some PWDstudents neither OBC Nor General”.

And at the end of the course they will conduct the examination ,and whose pass the examination they can take the admission of the first-year course of engineering in the similar Institution or else they can come out of the preparatory course and they can again repeat the procedure if they want to apply forthe preparatory course once reiterated?

Good luck and I hope it helps you.