How do I know whether I should use the singular or plural form of contribution?
I did an exercise. The …………… of artists could not be exaggerated.
The answer is contribution.
Why didn't it use the plural form?
Either singular or plural is correct. (Based on context and meaning.)
It depends on if you are expressing it as a mass noun or a countable noun.
If you want to emphasize individual contributions, you would use the plural:
Among all of the artists, eleven different contributions were made.
If you want to emphasize the idea of contribution in general (the totally if what was contributed or its nature), you would the singular (from Merriam-Webster):
The money was raised by voluntary contribution.