What is true regarding muscles?

Muscles play a crucial role in providing movement of body parts, which makes this statement accurate. The muscular system is responsible for all voluntary movements, such as walking and grasping, as well as involuntary movements, such as the beating of the heart and the movement of food through the digestive system. Muscles contract and relax in response to signals from the nervous system, allowing for a wide range of motion and coordination in activities. This function is essential not only for mobility but also for overall physiological processes in the body.

Other options suggest functions that are either incorrect or incomplete. For instance, saying that muscles have no impact on body movement overlooks their primary role in enabling such movements. Additionally, while muscles do contribute to posture, saying they only help with posture ignores their other critical functions. Lastly, the idea that muscles are not involved in bodily functions undermines their importance in various systems, such as the cardiovascular and digestive systems, where muscle contractions are essential for function.