The correct answer is: B. turpentine
Turpentine is a visually dense substance because it has a high refractive index. This means that light bends when it passes through turpentine, which makes it appear thicker than it actually is.
Air, benzene, and water are all less visually dense than turpentine. This is because they have lower refractive indices. Light does not bend as much when it passes through these substances, so they appear thinner than they actually are.
Refractive index is a measure of how much light bends when it passes from one medium to another. The refractive index of a substance is determined by its density and the wavelength of light.
The refractive index of air is 1.0003, the refractive index of benzene is 1.501, the refractive index of water is 1.333, and the refractive index of turpentine is 1.474.
As you can see, the refractive index of turpentine is higher than the refractive indices of air, benzene, and water. This means that light bends more when it passes through turpentine than it does when it passes through air, benzene, or water. This is why turpentine appears thicker than it actually is.