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