Arrange the following in the increasing order of relative concentration of dissolved oxygen in lake water: (A) Oligotrophic lakes (B) Eutrophic lakes (C) Mesotrophic lakes (D) Hypereutrophic lakes
Choose the correct answer from the options given below:

Correct option is B

Explanation:
The concentration of dissolved oxygen (DO) in lakes is influenced by their trophic status (nutrient levels and biological productivity):
· Hypereutrophic lakes (D): Extremely nutrient-rich, often resulting in algal blooms and decomposition, which depletes oxygen. → Lowest DO
· Eutrophic lakes (B): High productivity, more organic matter and decomposition → Low DO
· Mesotrophic lakes (C): Moderate nutrients and productivity → Moderate DO
· Oligotrophic lakes (A): Low in nutrients, clear water, less organic decomposition → Highest DO
Thus, the increasing order of dissolved oxygen is: (D) < (B) < (C) < (A)
Information Booster:
· Dissolved oxygen (DO) is crucial for aquatic life.
· High productivity lakes (eutrophic/hypereutrophic) may appear rich in life but often suffer oxygen depletion due to decomposition of organic material.
· Oligotrophic lakes support less biomass but maintain higher oxygen levels throughout.
Additional Information:
· (a) (A), (B), (C), (D) – Incorrect; this is the decreasing order of DO.
· (c) (A), (C), (B), (D) – Incorrect; this is the reverse of the correct increasing order.
· (d) (D), (C), (B), (A) – Incorrect; (C) should be after (B), not before.