Consider the following:
1. Catalytic convertor
2. Use of high compression ratio
3. Oxidation catalyst in the exhaust manifold
4. Use of high degree of supercharger
By which of these techniques, can the oxides of nitrogen in the exhaust be controlled?1
1 only
2
2 and 4 only
3
2, 3 and 4 only
4
1, 2, 3 and 4