circe gives odysseus several warnings before he leavesa. What does she warn about the sirens?Scylla and Chary bdis? The Sungod's cattle?

When Odysseus returns, Circe tells him to follow one of two alternative paths leading back to Greece: toward the "Wandering Rocks" where King Aeolus (god of the winds) reigned or passing in between the Scylla monster and a giant whirlpool. In regards to the sirens, she tells him to block his ears with wax so he cannot hear them.

His choices in his upcoming adventure

scylla and charybdis (scylla is a monster, charybdis is a whirlpool) or the wandering rocks that are impossible to pass

the sirens and how to prepare

hyperion's (Apollo/the sun-god, same god) cattle, not to eat them

to not eat the cattle of the sun god, lord helios, lest he pay in death.

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She warns him of impending dangers, such as the Sirenes, who bewitch men with their melodic singing, as well as the unsurpassable rocks, called Drifters, and the monstrous Scylla, an abominable creature with twelve legs and six heads sporting terrifying fangs. Circe advises Odysseus not to fight but to push on, even if it means losing men --or, he can take a detour and confront Charybdis, a massive whirlpool that can swallow their entire ship. After these dangers lies the island of Thrinakia, inhabited by Helios’s immortal cattle. Once again, Odysseus is told not to touch these sacred kine (or cows). Circe also mentions Phaethousa and Lampetia, sweet nymphs from Helios and Neaira who take care of the cattle. However, Circe’s words of caution are overshadowed by an ominous presage: she tells him that he will face long, lonely years after this episode. Her advice also seems to come with other relaxing, enjoyable, and maybe slightly inappropriate activities.