The sea appears blue

The sea appears blue primarily due to the scattering of sunlight by water molecules and suspended particles (option B). When sunlight enters the water, it interacts with these substances, causing shorter blue wavelengths to scatter more than longer wavelengths. This scattering phenomenon results in the predominant reflection of blue light back to our eyes, giving the sea its characteristic blue hue. Depth plays a secondary role; while deeper water may appear darker due to reduced light penetration, the initial perception of blue color is determined by surface interactions. The color of the water itself (option C) is influenced by the absorption and scattering of light, but pure water appears colorless—it’s the scattering and reflection that create the perception of blue. The reflection of the sky (option B) also contributes, as the blue sky is reflected off the water’s surface, enhancing the overall blue appearance. Therefore, the blue color of the sea is primarily a result of light scattering and reflection processes, rather than solely depth or inherent water coloration.