Parenthetical Plurals
7.8.4 Parenthetical Plurals
When -s or -es is added parenthetically to a word to express the possibility of a plural, the verb should be singular. However, in most instances it is preferable to avoid this construction and use the plural noun instead.
Acceptable: |
The risk factor(s) for each study participant was not always clear. |
Better: |
The risk factors of the study participants were not always clear. |