Answer:
D. That the reader has the background knowledge to understand the allusion
Explanation:
If there is an allusion to Venus the goddess of beauty, the counterpart of Aphrodite(Greek Mythology), someone who does not have any background knowledge about Roman mythology or mythology in general would assume the writer is referring to Venus, the planet rather than the goddess.
In order to understand an allusion as used by a writer, the reader must have adequate knowledge as this was expected of the reader by the writer.