Answer:
a. A religion.
Step-by-step explanation:
I don't know what word is underlined, but I'm assuming it's "polytheism." (This sounds like it's from Virginia Woolf, who I love (no not in a weird way).) Polytheism means worshipping many gods. You can understand this in context by reading what she says next: "When people stopped believing in the gods, they no longer had power." This points you to the understanding that this is a religion.