Who is responsible for opening the MCD during normal operations on the ERJ 175?

The correct answer identifies the Customer Service Agent (CSA) as responsible for opening the Main Cabin Door (MCD) during normal operations on the ERJ 175. In the operational workflow of a commercial aircraft, especially during boarding and deplaning, it is usually the CSA who handles the ground operations related to the passenger's entry and exit from the aircraft. This role includes ensuring that the area around the door is clear and safe for passengers as they embark or disembark.

The CSA's responsibility typically aligns with ensuring compliance with safety protocols and operating procedures specific to the aircraft and airport operations, thereby allowing flight attendants and pilots to focus on their onboard duties.

In contrast, while flight attendants assist with passenger boarding and deboarding, they are not usually responsible for physically opening the MCD. The captain generally oversees aircraft safety and operation but does not handle doors directly during normal ground operations. Passengers certainly do not have the authority or responsibility to open the MCD, as such actions are regulated for safety reasons.