It turns out that many materials can be solid at a higher temperature if the pressure is also higher. so even though it is hotter in the inner core the pressure in the core is also higher and you can have a solid iron nickel instead of liquid
I think that since it lives on the ocean floor, at the deepest of the ocean. So anyway, the fin on the Eurypterids is still necessary but not that much, since they live on the ocean floor. Their movements mostly on the ocean floor. So fin would not help them "stick" to the floor. Also there are still gravity acts on the Eurypterids and the feet would help them move faster. Hope this helps.
Answer: Option C) Root hairs have an elongated shape that increases the surface area-to-volume ratio.
Explanation:
The larger surface area-to-volume ratio of root hairs enables them to rapidly absorped water molecules and nutrients along their elongated shape while aiding their upward transport from the root up the shoot (through the xylem vessels).