Answer:
A. Lake
Explanation:
We need to recall that the water which contains less than 1% salts is called as freshwater.
In lakes water comes from rain, melting of ice from mountains, seepage of ground water, and water streams. These all are fresh sources of water. Therefore, A is the right answer.
B is not the right answer because river water dissolves salts while passing through the stones and riverbeds. So, water is not always fresh in rivers.
C is not correct, because ocean water contains a huge amount of salts.
Although streams have fresh water but they also have small size. Therefor, D is also not right answer.