During normal operations, who is responsible for opening the MCD on the ERJ 175?

The correct choice reflects the role of the Customer Service Agent (CSA) in handling ground operations, including the opening of the Main Cabin Door (MCD) on the ERJ 175 during normal operations. The CSA's responsibilities typically encompass managing passenger boarding and deplaning, ensuring safety protocols are followed, and facilitating smooth operation at the gate.

In the context of opening the MCD, the CSA is trained to handle this task as part of their duties when the aircraft is on the ground, prior to boarding or after arriving. They coordinate with the flight crew and ensure that the operation aligns with safety standards and procedures.

Other roles, such as the Flight Attendant, Captain, or Purser, also have responsibilities related to safety and operational efficiency but typically engage in the process at different stages or in unique capacities, such as in-flight service or command decisions during flight operations. The CSA's specific training and focus on ground operations make them the correct choice for this task during normal flight operations at the airport.