In RRB JE there are some posts for the Degree student of sciences thats the reason why its mentioned 3 years degree. On the final year of your BTech you can apply i.e., you are eligible for RRB JE 2022.
To know more about RRB JE visit the link below:
https://competition.careers360.com/exams/rrb-je-recruitment
I hope this answer helps. All the very best for your future endeavors!
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