Answer :
an estuary is a partially enclosed "lake" that is open to the ocean also has rivers and streams running into it. so D. an area where ocean water mixes with fresh water best describes an estuary.
Answer: D. an area where ocean water mixes with fresh water.
Explanation:
An estuary is a coastal water body. It can be define as a transition zone or area where river and ocean water meet. Hence, the water of estuary is brackish because it is a combination of freshwater from river and saline water from ocean.