What does a two-axis autopilot primarily monitor and control in an aircraft?

A two-axis autopilot primarily monitors and controls pitch and roll, which are crucial components of an aircraft's attitude and stability in flight. The pitch refers to the angle of the aircraft's nose up or down relative to the horizon, affecting the altitude and climb/descent rates. The roll indicates the angular rotation of the aircraft around its longitudinal axis, which is essential for maintaining level flight and making turns.

By managing these two axes, the autopilot can help the pilot maintain a steady flight path without constant manual adjustments. This is particularly valuable during long flights, where pilot workload can be reduced, allowing for better focus on other aspects of flight management. Unlike other options that focus on various aspects of flight (such as yaw, speed, headings, or altitude), pitch and roll control are specific to maintaining the aircraft's orientation and are the primary responsibilities of a two-axis autopilot system.