Which of the following represent the correct equations for trichromatic coefficients?

• A. x=X/(X+Y+Z), y=Y/(X+Y+Z), z=Z/(X+Y+Z)
• B. x=(Y+Z)/(X+Y+Z), y=(X+Z)/(X+Y+Z), z=(X+Y)/(X+Y+Z)
• C. x=X/(X-Y+Z), y=Y/(X-Y+Z), z=Z/(X-Y+Z)
• D. x=(-X)/(X+Y+Z), y=(-Y)/(X+Y+Z), z=(-Z)/(X+Y+Z)