Final answer:
Service members typically wear the physical training uniform for both the FEP weigh-in and the BCA portion of the PFA, adhering to their branch's specific regulations.
Step-by-step explanation:
The Fitness Enhancement Program (FEP) and the Body Composition Assessment (BCA) are both components of the Physical Fitness Assessment (PFA) within various military branches. For the FEP weigh-in, service members are generally expected to wear the physical training uniform (PTU) or similar fitness attire as per their specific branch guidelines. However, for the BCA portion of the PFA, members must wear the standard Physical Training Uniform (PTU) or as specified by their branch's regulations, which commonly includes shorts and a t-shirt, without shoes or additional layers that could affect the measurement.