BOD values (in ppm) for clean water (A) and polluted water (B) are expected respectively as:

Biochemical Oxygen Demand (BOD):

BOD is the amount of oxygen required by bacteria to decompose the organic matter present in a given sample of water.

Key Criteria as per NCERT:

Clean Water ($$A$$): Clean water has a low concentration of organic waste, so it requires very little oxygen for decomposition. The BOD value for clean water is less than $$5\text{ ppm}$$ ($$A < 5$$).

Highly Polluted Water ($$B$$): Highly polluted water contains a large amount of organic matter, resulting in high bacterial activity and high oxygen consumption. The BOD value for polluted water is greater than $$17\text{ ppm}$$ ($$B > 17$$).

Therefore, the expected BOD values are $$A < 5\text{ ppm}$$ and $$B > 17\text{ ppm}$$.

Hence the correct option is A.