Hi

THE question is certainly open ended.

Procedure

1. Before passing out parade, there is a choice of arm conducted by manpower planning of army HQ.
2. THE gentleman cadet needs to give three choices of arms and services.
3. Whatever he gives, he needs to give three choices of infantry regiments.
4. Rest, manpower planning has calculations and depending upon the merit the regiment or arm or services is awarded.

Hope it helps