Major muscle groups. These work in pairs or coordinated groups.

Major muscle groups. These work in pairs or coordinated groups.

• A. Muscles
• B. Arthritis
• C. Skeletal muscles
• D. Bones

Answer: (C)

Movement relies on skeletal muscles, the voluntary, striated muscles that attach to bones and pull to move joints. They typically work in opposing pairs or coordinated groups around a joint, so when one contracts the other relaxes to produce smooth, controlled action. For example, bending the elbow uses the biceps to flex and the triceps to extend, working together to create the motion. The other options don’t fit this idea: simply “muscles” is too broad and also includes types that don’t move joints in paired actions; bones are the structures that move, not the muscles; arthritis is a condition affecting joints, not a muscle group.

Movement relies on skeletal muscles, the voluntary, striated muscles that attach to bones and pull to move joints. They typically work in opposing pairs or coordinated groups around a joint, so when one contracts the other relaxes to produce smooth, controlled action. For example, bending the elbow uses the biceps to flex and the triceps to extend, working together to create the motion. The other options don’t fit this idea: simply “muscles” is too broad and also includes types that don’t move joints in paired actions; bones are the structures that move, not the muscles; arthritis is a condition affecting joints, not a muscle group.