The kinds of hand and wrist injuries that result from extended use of a computer while maintaining an incorrect posture are common among schoolchildren in Harnville. Computers are important to the school curriculum there, so instead of reducing the amount their students use computers, teachers plan to bring about a sharp reduction in the number of these injuries by carefully monitoring their students' posture when using computers in the classroom. Which of the following would it be most useful to know in order to assess the likelihood that the teachers' plan will be successful? ['What proportion of schoolchildren in Harnville with hand and wrist injuries use computers extensively outside the classroom', "Whether changes in the curriculum could reduce the schools' dependence on computers", 'What proportion of schoolchildren in Harnville already use correct posture while using a computer', 'Whether hand and wrist injuries not caused by computer use are common among schoolchildren in Harnville']