I, an American writer, writing about America, was working from memory, and the memory is at best a faulty, warpy reservoir. What does the descriptive detail in this passage show about the author’s purpose?

It shows that the writer is getting old and needs to see the country while he still can, which shows why he needs to travel.
It shows that the writer does not remember how to write, so he should stop writing and travel instead.
It shows that the writer’s memory is imperfect and sets up the reason for the trip.
It shows that memory is better than other sources for effective writing, so he wants to have more memories.