The correct answer is option 4: Sound waves cannot travel through a vacuum.

Option 1 states that sound waves can travel through water, which is correct. Sound waves are able to propagate through any medium that has particles to transmit the vibrations. In water, sound waves travel by creating pressure disturbances that move through the water molecules.

Option 2 states that sound waves can travel through air, which is also correct. Air is one of the most common mediums through which sound waves propagate. The vibrations caused by sound create pressure variations in the air, allowing the sound to be transmitted.

Option 3 states that sound waves can travel through steel, which is true. Steel is a solid and sound waves are able to travel through solids as well. The particles in the solid medium vibrate in response to the sound waves, transmitting the sound.

Option 4, which is the correct answer, states that sound waves cannot travel through a vacuum. A vacuum is a space devoid of matter, including air or any other medium. In the absence of particles to transmit the vibrations, sound waves cannot propagate in a vacuum.