In Photoshop Red=0 + Green=0 + Blue=0 --- the output is pure Black.

Correct Answer : B.

Rich Black vs Pure Black:
It may vary case to case but most all CMYK programs will use pure black as the default black color, which is traditionally composed of 100% black and no other inks used. Then we have rich black. Rich black is often regarded as a color that is “blacker than black”. Although it varies between printers, rich black  is an ink combination of the following ink percents: 50% Cyan, 50% Magenta, 25% Yellow, and 100% Black. However, there are many different possible ink combinations that create colors such as “Cool Black” (60% Cyan, 0% Magenta, 0% Yellow, 100% Black) and “Warm Black” (0% Cyan, 60% Magenta, 30% Cyan, 100% Black).