Step 1: Rank the options by how "hands-on" they are.
Reading, watching, and discussing are all forms of gaining information; only one option describes an actual physical action.
Step 2: Apply the "learning by doing" principle.
Environmental education becomes effective only when knowledge turns into a repeated habit, such as sorting waste at home or school every day.
Step 3: Confirm the practical outcome.
Segregating organic from inorganic waste lets recyclables be reused and biodegradable waste be composted, cutting the pollution load directly.
Final Answer:
The practice-based option (D) is the one that actually reduces pollution.