The angular displacement between two interconnected stations is mainly due to

The angular displacement between two interconnected stations refers to the phase angle difference between their terminal voltages.

While armature reactance and synchronous reactance of alternators do contribute to this displacement, their effects are relatively small compared to the impact of the interconnecting transmission line.

The primary cause is the reactance of the interconnector. This reactance causes a voltage drop proportional to the power transmitted, which directly changes the phase angle between the two stations.

The higher the interconnector's reactance, the greater the angular displacement for the same amount of transmitted power.

Therefore, the main reason is the reactance of the interconnector, making Option B correct.