Alex works at his computer for several hours a day. He is careful to sit up straight at the computer with his feet on the floor and to keep his muscles relaxed, and stays off his computer after 6 p.m. For what kind of computer-related health problems is Alex still at risk? Select all that apply.
1. musculoskeletal problems
2. vision problems
3. sleep problems
4. headaches
1. musculoskeletal problems
2. vision problems
4. headaches