Which one of the following arrangements for the sequence of the main components of a Uv/visible spectrophotometer is Correct?

Which one of the following arrangements for the sequence of the main components of a Uv/visible spectrophotometer is Correct?

A. Light source  Detector  Sample cell  Monochromator  Readout
B. Light source  Sample cell  Detector  Monochromator  Readout
C. Light source  Readout  Sample cell  Detector  Monochromator
D. None of these