Which of the following paris is NOT correctly matched?

1. A

   Renneting-Cheese

   Renneting is the use of rennet enzymes to coagulate milk in cheese making. The pair with cheese is correctly matched. This option is not the unmatched one.

2. B

   Genetic Engineering-Plasmids

   Plasmids are extra-chromosomal DNA circles widely used as vectors in genetic engineering. The pair is correctly matched. This option is not the key.

3. C

   Golden rice-Vitamin A

   Golden rice is genetically engineered to accumulate beta-carotene, a precursor of vitamin A, in the grain. The pair is correctly matched. This option is not the key.

4. D

   Ozone layer-Troposphere

   The ozone layer is in the stratosphere, not the troposphere. Pairing the ozone layer with the troposphere is therefore wrong. This unmatched pair is the official key.

Summary. Official key is (d) Ozone layer–Troposphere. Cheese uses rennet, plasmids are genetic-engineering vectors, and golden rice is a vitamin-A biofortified crop, so (a), (b) and (c) are correctly matched. The protective ozone maximum is stratospheric. Only (d) is incorrectly matched.