Question

Sediment is deposited as a river enters a lake because the

Answer 1

I believe that the answer is number 1. Sediment is deposited as a river enters a lake because the velocity (speed) of the river decreases - the same reason that sediment gets deposited on a river's meander.

Hope this helps! :)

Answer 2

The correct answer is - (1) velocity of the river decreases.

When the velocity (the speed) of the river decreases, be it at the entry of a lake, sea, ocean, or meandering, passing through a valley with very little change in altitude, the sediment starts to get deposited. This is due to the decrease in force caused by the decrease in velocity, there is not enough force to push the sediments further so they start to deposit because the river is not able to drag them further on.