The OP is a rising MS-III in Army ROTC based on prior posts.
The summer after your MS-III year is a critical one for your branching future. Your OML is greatly affected by both GPA and your performance in Advanced Camp. Once your OML evaluation is completed, you will be asked to submit a list ranked by your preference for your branch choices. The higher you rank on the OML, the more likely you are to get your first choice.
For instance, if you branch Armor, how can you choose whether you're in a tank platoon or cavalry?
I will speak to Armor as my DS is about to enter Armor BOLC.
The correct terminology in Armor is "Heavy
" (for tanks) and "Light
" (for scout cavalry - Bradleys and Strykers). You won't know until you are partially through Armor BOLC. Your performance ranking in BOLC will dictate if you get a choice or not. They will decide "Heavy" versus "light" armor midway through BOLC by your performance.
This is why Armor 2LT's don't know their permanent duty station until they are done with BOLC.