Answer:
black
Step-by-step explanation:
Among the visible electromagnetic spectrum, the piece of paper absorbs all the colours, so it will not reflect any colour from the spectrum of light which comprises violet, indigo, blue, green, yellow, orange and red thus will appear black.
Any object appears of the same colour which it does not absorbs from the white light but reflects back to our eyes.
An object partially absorbing all colours of the light will appear to be grey in color.