Answer: option A - Oxygen from the humid air chemically reacted with the iron in the frame, creating rust, a new substance with different properties.
Step-by-step explanation:
Rusting refers to the deteriorated state of IRON as a result of moisture (water molecules) and oxidation (addition of oxygen)
For example: The rust on a bicycle chain can make cycling to work very difficult.
Also, note that RUST has a reddish-brown color. So, RUSTING has affected Diane's bicycle