Final answer:
Neptune was named after the Roman sea god because its distinct blue color resembles the ocean. This coloration is a result of sunlight scattering in the upper atmosphere of the planet, as photographed by Voyager in 1989. The name is rooted in mythology and symbolism, and is not necessarily indicative of the planet's composition or discovery location.
Step-by-step explanation:
Why was Neptune probably named after the Roman sea god? Among the presented options, the correct answer is C) Because it's blue like the ocean. Neptune was likely named after the Roman sea god because of its distinct blue color. This blue hue is due to the scattering of sunlight in the planet's upper atmosphere, as seen in photographs from Voyager in 1989. While Neptune does have a considerable amount of water, its name is not directly related to its composition.
The discovery of Neptune itself is a testament to the power of gravitational theory and the precise predictions made by mathematicians that led to its identification. It's notable that the planet was discovered by Johann Galle in 1846 on the very night he received a suggestion to look for it near a predicted location, making its naming momentous beyond just its color resemblance to the ocean.
The naming of celestial bodies often reflects mythological or symbolic associations and for Neptune, its striking blue made the association with the god of the sea, a fitting tribute.