Explanation:

- Passage Context: The passage describes an elephant, Chinna Thambi, taking a shower with something and later drinking water from beneath a rock.

- Blank (3) Context: Within the passage, "The (3) ______ was green; not the kind people would drink," suggests what's being described is something seen in nature but non-potable for humans.

- Option 1: water: This option is relevant as natural water sources, like ponds or lakes, can often appear green due to algae or other factors, and are typically non-drinkable for humans.

- Option 2: milk: Unlikely, since milk is not something found naturally in the environment and doesn't naturally appear green.

- Option 3: flower: Though flowers can be green, the phrase "not the kind people would drink" doesn't apply to flowers.

- Option 4: leaf: Similar to flowers, leaves can be green, but the context of drinking does not fit.

- Correct Answer: Option 1, water: This makes sense in the context, describing non-drinkable, green water.