• "Multi-crew cooperation" (MCC) means the functioning of the flight crew as a team of cooperating members led by the pilot-in-command.

To go through the other options:

• "a management system in which the flight crew makes optimum use of all the available resources both on ground and in the aircraft."
  • It looks like that this is describing CRM (Crew Resource Management), an important part of learning MCC (Multi-Crew Cooperation), but not the definition.
• "the functioning of the flight crew as a team of cooperating members lead by the pilot-in-command."
  • Correct. This is the exact definition of MCC as shown above from Part-FCL.
• "a method of avoiding undesired aircraft states by identifying and managing threats and errors."
  • This is one we made up to fill in the gap in feedback, it is a loose definition of threat and error management.
• "a management style where the pilot-in-command controls all the decisions and takes very few inputs from other crew members."
  • Another one we made up, a definition of an autocratic leadership style in the cockpit.