Arrange the given organisms involved in an ecosystem in correct sequence from lower to higher order.

(A) Fish
(B) Phytoplankton
(C) Man
(D) Zooplankton

Choose the correct answer from the options given below.

(B), (D), (A), (C)

The correct answer is Option (2) → (B), (D), (A), (C) 

The correct sequence of organisms in an ecosystem from lower to higher trophic order is:

• Phytoplankton (B) are primary producers (autotrophs) at the base of the food chain.
• Zooplankton (D) are primary consumers (herbivores) that feed on phytoplankton.
• Fish (A) are secondary consumers (carnivores/omnivores) that feed on zooplankton.
• Man (C) is a tertiary consumer (top carnivore/omnivore) that may feed on fish.

Thus, the sequence is: Phytoplankton → Zooplankton → Fish → Man
Which corresponds to: (B), (D), (A), (C)