Study the table carefully and answer the following questions.
Investigation on Rusting of Iron:
| Iron Object | Condition | Observation after One Week |
| A | Kept in dry air | No rust formed |
| B | Kept in water only (boiled water covered with oil) | No rust formed |
| C | Kept in air and water | Reddish-brown rust formed |
| D | Painted and exposed to rain | No rust formed |
| E | Coated with oil and kept in moist air | No rust formed |
1. Why was no rust observed on Object D? -
2. Which objects demonstrate methods of preventing rusting? -