Which of the following should a lead flight attendant communicate to the cockpit?

The appropriate communication to the cockpit primarily revolves around ensuring safety and addressing any significant developments that may impact the flight. When it comes to significant passenger issues and emergencies, it is crucial for the lead flight attendant to relay this information to the cockpit immediately. This can include situations such as medical emergencies, unruly passengers, or any other occurrences that may necessitate the attention of the pilots for the safety of everyone on board.

Communicating significant passenger issues enables the flight crew in the cockpit to make informed decisions regarding the flight’s operation. They may need to adjust flight plans, prepare for potential emergencies upon landing, or enhance their situational awareness of the cabin environment.

The other options, while relevant to the overall flight operation, do not carry the same level of urgency and direct impact on safety as communicating significant passenger issues and emergencies. Flight departure times and meal preferences are managed through other channels within the airline's operational structure, while weather conditions are generally monitored by the pilots through various instruments and systems.