Oxides of nitrogen occur in the environment because of both natural and human-made sources. Which row is correct?
- Anatural source: electrical discharges in the atmosphere; man-made source: internal combustion engines
- Bnatural source: electrical discharges in the atmosphere; man-made source: as a by-product of the Haber process
- Cnatural source: decomposition of dead plants in rivers; man-made source: internal combustion engines
- Dnatural source: decomposition of dead plants in rivers; man-made source: as a by-product of the Haber process