Final answer:
Mountains came from Ymir's bones according to Norse mythology as described in the Prose Edda, specifically by the gods Odin, Vili, and Ve.
Step-by-step explanation:
From Ymir's bones came mountains, which is option c in the multiple-choice question based on the Prose Edda, a text that is a key source for Norse mythology. The Prose Edda is a valuable collection of mythological and heroic poems, essential for understanding the belief system and culture of the Norse people. Ymir was a primeval being in Norse cosmogony, and his body parts were used to form various elements of the world by the gods Odin, Vili, and Ve.