Hello Mohit,

As your question is related to discipline column of CAT exam application form so first of all we should know about  what is discipline in application form of CAT exam.

So discipline means a grouping of courses that share common academic or vocational preparation,which is typically defined by degree or degrees or specific professional preparation.

Therefore according to the definition that is given in above paragraph you have to mention your stream of degree. As you completed b.tech in electronics and communication so you should fill engineering at the column of discipline in the CAT application form.

Best of luck for your career.