Which of the following statements about waves is true?

The statement that all waves carry energy, but not all waves are mechanical, is accurate and reflects a fundamental concept in the study of waves. Different types of waves exist, and they are generally categorized into mechanical waves and electromagnetic waves. Mechanical waves, such as sound and water waves, do indeed require a medium (such as air, water, or solid materials) to propagate. However, electromagnetic waves, which include light, radio waves, and X-rays, do not need a medium; they can travel through the vacuum of space.

This distinction is crucial because it clarifies that while all waves have the common characteristic of carrying energy, their modes of transmission can differ significantly. Mechanical waves transfer energy by causing the particles of the medium to oscillate, while electromagnetic waves transmit energy through oscillating electric and magnetic fields.

The other statements do not accurately encompass the full range of wave phenomena. For instance, saying that waves require a medium to travel does not apply to all wave types, and the claim that waves can only travel through solids limits the understanding of how waves propagate, as they can travel through liquids and gases as well. Additionally, stating that waves never change the physical properties of the medium overlooks how certain waves can influence the medium's state or dynamics,