Which of the following items must be coordinated verbally or put in the 4th line when required?

The requirement to coordinate verbally or document specific details in the 4th line is crucial for ensuring the safety and efficiency of radar operations. The correct answer encompasses heading, speed, and weather deviations, as these elements are critical for maintaining situational awareness and ensuring proper communication between personnel involved in the radar operations.

Clear communication about heading is essential for maintaining the right flight path, while speed adjustments can significantly impact a flight's trajectory and fuel consumption. Weather deviations, on the other hand, are vital for avoiding hazardous conditions that could pose risks to safety and operational effectiveness. By mandating that all three of these components be coordinated, the procedure emphasizes comprehensive information sharing to prevent misunderstandings and enhance overall operational safety.

The other options focus on fewer elements. For instance, coordinating just the heading and destination, or only speed and heading, would lack important context that can arise from weather variations. Thus, only knowing some of the critical factors could lead to an incomplete synchronization of operations. Therefore, including heading, speed, and weather deviations ensures that all relevant information is shared during routine and abnormal operations, fostering a safer and more proficient operational environment.