0.8 : 0.12 = 2 :?

Each of the following statements regarding fundamentals of panoramic radiography is correct except one. Which one is the exception?

A) The rotational center is the axis on which the tube head and the cassette rotate. B) The x-ray source and the film remain stationary. C) They are based on the principles of tomography. D) The x-rays emerge from a narrow, vertical slit in the tube head.

Which of the following describes the collimator of the panoramic x-ray beam?

A) It is circular (round). B) It is concentric (cone shaped). C) It is rectangular. D) It is a narrow slit.