In total reflection X-ray fluorescence spectrometer, the specimen is excited by the primary X-ray beam at a grazing angle _______ the critical angle.

In total reflection X-ray fluorescence spectrometer, the specimen is

1.	In total reflection X-ray fluorescence spectrometer, the specimen is excited by the primary X-ray beam at a grazing angle _______ the critical angle.
A.	Greater than
B.	Less than
C.	Equal to
D.	Which is a complement of
Answer» C. Equal to