Final answer:
First-year students travel from Hogsmeade Station to Hogwarts castle in what appears to be horse-drawn carriages; these are actually Thestral-drawn carriages, which are invisible to those who have not witnessed death.
Step-by-step explanation:
The question asks how first-year students travel from Hogsmeade Station to Hogwarts castle. The correct answer is B) Thestral-drawn carriages. However, it should be noted that these carriages appear to be horseless to anyone who has not witnessed death, so for most first-year students, the carriages seem to move by magic. It's only later in the series that we learn that they're pulled by Thestrals. Therefore, all students, except for those who can see Thestrals, would believe they are simply using horse-drawn carriages or enchanted carriages. The Hogwarts Express is the train that brings students from London to Hogsmeade Station, but not to the castle itself.