Which option allows you to change the guide path of an animation so it travels in a straight line?

The option that allows you to change the guide path of an animation to travel in a straight line is spatial interpolation set to linear. When you apply linear interpolation to keyframes in After Effects, it ensures that the motion is uniform and travels in straight lines between the specified points. This results in a smooth, direct path without any curves.

In contrast, Bezier interpolation creates smooth curves and can result in non-linear motion as it utilizes the Bezier handles to control the curvature and angle of the motion path. Path Animation refers to the overall process of animating an object along a defined path but does not specifically dictate the nature of that path (linear or otherwise). Keyframe Adjustment allows you to modify the timing and values of keyframes but doesn't inherently determine the shape or type of path the animation takes. By selecting linear spatial interpolation, the path directly becomes straight, making it the correct choice for achieving that effect.