Consider the following statements:1.Agricultural soils release nitrogen oxides into environment.2.Cattle release ammonia into environment.3.Poultry industry releases reactive nitrogen compounds into environment.Which of the statements given above is/are correct?

1. A

   1 and 3 only

   (a) 1 and 3 only. Agricultural soils do emit nitrogen oxides, and poultry does release reactive nitrogen, but cattle ammonia is also a major pathway, so dropping statement 2 is not the key.

2. B

   2 and 3 only

   (b) 2 and 3 only. Drops soil NOx, which is a recognised agricultural emission, so this is not the key.

3. C

   2 only

   (c) 2 only. Incomplete, so not the key.

4. D

   1, 2 and 3

   (d) 1, 2 and 3. Fertilised soils emit NOx/N2O-related nitrogen oxides; livestock urine and dung emit ammonia; poultry operations emit ammonia and other reactive nitrogen. All three statements are correct, so this is the official key.

Summary. Official key is (d) all three. The nitrogen cascade links fields, cattle and poultry to NOx, ammonia and other reactive nitrogen in air and water. Honour the stored letter (d).