Correct vertical angulation should ensure that:

The correct answer ensures that both palatal and buccal cusps are on the same horizontal plane, which is crucial for achieving an accurate representation of the dental structure in radiographs. Proper vertical angulation is necessary to avoid distortions in the image that can occur when the x-ray beam is directed at an incorrect angle. This alignment allows for an optimal view of the teeth and their anatomy, aiding in diagnosis and treatment planning.

When the angulation is correct, it helps to achieve a true representation of the anatomical landmarks, ensuring that the image captures the dimensions and positions of the cusps accurately. This is essential for assessing conditions or planning further dental procedures. Therefore, aligning the cusps on the same horizontal plane as a result of correct vertical angulation facilitates better clarity and reliability in the diagnostic process.