Option a) is correct
Step-by-step explanation:
Growing improved crop plants that have nitrogen fixing enzymes
- Nitrate pollution occurs because of the introduction of excessive amounts of nitrogen to ground water and surface water
- Use of synthetic fertilizers has resulted in high levels of pollution and eutrophication of lakes and rivers
- When nitrogen fertilizers are leached deep down into the soil they cause serious pollution problems
- Plants that can do nitrogen fixation include members of family Fabaceae
- The symbiotic association between legumes and Rhizobium is the most important nitrogen fixing association; rhizobia bacteria convert nitrogen gas to ammonia and this process is called nitrogen fixation