The matter in the methane seas on saturn's moon titan exists mostly in which state of matter?

The correct answer is - liquid state.

The seas on Saturn's Moon, Titan, are mostly composed out of methane, a liquid methane to be more specific. The methane is in liquid form because of the conditions on the moon, where it is very cold, which turns the methane into a liquid state, instead of the gas state as we have it here on Earth. The seas on Titan, compared with the seas on the Earth, are not big seas, more like small and medium sized seas, but the amount of liquid they contain in them is very big, and they can easily fill the biggest lakes on our planets with it.

answer; (d) melting of sea ice;