The major and most effective way of controlling pollution is to

Step 1: Analyze the question The question asks for the major and most effective way of controlling pollution. Every option helps, but we need the one that tackles the problem at its root.

Step 2: Consider each option

• A. Improve machinery: This reduces harmful emissions from combustion, but it covers only one source of pollution (engines, generators, industry). It is limited in scope.
• B. Pass strict laws: Laws are useful, but in many places they are hard to enforce, and people may break them if they don't understand why they matter.
• C. Educate people on the causes and effects of pollution: When people understand how pollution happens and how it harms health and the environment, they change their behaviour. This covers individuals, companies, and governments, and it supports all the other measures. Laws are obeyed better, and cleaner technology is adopted more willingly.
• D. Convert chemical wastes to harmless substances: This is a good treatment method, but it applies only to chemical wastes from industry, not to all pollution (refuse dumping, gas flaring, vehicle fumes, oil spills).

Step 3: Choose the answer Education is the broadest and most lasting approach. It changes attitudes and behaviour, which is the root of most pollution.

Answer: C

Exam tip: For "major," "most effective," or "best way" questions on environmental issues, look for the option that addresses the cause, such as awareness, attitude, or behaviour. Options that deal only with one source or one type of waste are usually too narrow.