Step 1: Water Act (1974).
The Water Act was enacted first in 1974 to prevent and control water pollution.
Step 2: Air Act (1981).
The Air (Prevention and Control of Pollution) Act was enacted in 1981.
Step 3: Environmental Protection Act (1986).
This was enacted after the Bhopal Gas tragedy in 1984, as an umbrella legislation in 1986.
Step 4: National Green Tribunal Act (2010).
This was enacted in 2010 to provide a judicial mechanism for speedy environmental justice.
Hence, the order is: (ii) → (iii) → (i) → (iv).
Final Answer:
\[
\boxed{\text{(D) (ii), (iii), (i), (iv)}}
\]