1. CR Dhan 416: A rice variety suited for coastal saline regions - Correct. CR Dhan 416 is indeed a rice variety suitable for coastal saline regions and is resistant to diseases such as brown spot and rice tungro disease.
2. Durum Wheat Variety: Tolerant to heat and resistant to diseases - Correct. Durum wheat variety is developed for irrigated conditions in regions like Maharashtra, Karnataka, and Tamil Nadu, and is biofortified with higher levels of zinc and iron, along with being tolerant to heat and resistant to various diseases.
3. Nitrous Oxide: 300 times more potent than carbon dioxide as a greenhouse gas - Correct. Nitrous oxide is indeed 300 times more potent than methane and carbon dioxide as a greenhouse gas, posing a significant threat to the ozone layer.
4. Nitrogen Pollution: Does not affect biodiversity - Incorrect. Nitrogen pollution significantly affects biodiversity. Excess nitrogen can lead to soil acidity, ecosystem over-enrichment, and the creation of "dead zones" in oceans, thus degrading soil health and promoting toxic algal blooms that disrupt marine ecosystems.
Thus, only pairs 1, 2, and 3 are correctly matched.
Answer: Option B: Only two pairs