Answer:
All the three persons do no work while holding the books steady at their respective positions.
Explanation:
The work done by a force is given by
[tex]W=\overrightarrow{F}.\overrightarrow{dr}[/tex]
Since there is no dispalcement of the books we have work done equals
[tex]W=\overrightarrow{F}.0\\\\\therefore W=0[/tex]