After drifting off the 300-degree radial, what heading should you initially turn to regain the radial?

To regain the 300-degree radial after drifting off it, the appropriate initial heading to turn to is 320 degrees. This is because the radial you are trying to intercept is at 300 degrees, and to turn back toward it, you need to head slightly to the right of that radial's course.

When you drift away from a specific radial, you can determine your interception heading by considering the relative positions of the aircraft and the radial. Since radials are based on magnetic heading, to intercept a radial that is to the left or behind you, you must turn away from your current heading towards the radial. In this case, turning to 320 degrees gives you a heading that allows you to intercept the 300-degree radial from the right side, making the turn more effective in reestablishing the desired course. This initial turn will set you on a path to align with the 300-degree radial, which is your intended course.

Other options do not provide the correct angle to regain the radial efficiently, as they either turn you too far away or not enough towards the radial.