In salt wedge estuary:

Correct option is A

Correct Answer: (a) River flow is dominant
Explanation:
→ Salt wedge estuaries form when strong river discharge flows over denser seawater entering from below, creating a distinct wedge-shaped saltwater layer.
→ Limited mixing occurs due to strong freshwater flow.
Information Booster:
→ Common near large river mouths like Mississippi; wedge moves with tidal cycle.
Additional Information:
(b) Dominant tides form well-mixed estuaries.
(c) Describes partially mixed estuaries.
(d) Moderate flow → partial mixing, not wedge.