Thomas Edison's laboratory facility in Menlo Park most closely resembled a factory. The laboratory itself was one large open room with high ceilings made of narrow wood planks. A brick fireplace protruding from one wall provided heat for the dimly lit facility. However, this dull facade was merely a mask behind which hid the face of invention.

Which technique of fiction is used in this nonfiction excerpt?

1. Literary allusion is used to compare Edison's laboratory to a mythological setting.
2. Personification is used to suggest the importance of the building to Edison.
3. Metaphor is used to express that the work being done was more interesting than the building suggested.