The triangular-shaped body of water that forms where a streams enters a larger body of water is a/an
a. meander.
b. delta.
c. alluvial.
d. rejuvenation.

The best answer is B

Deltas are wet lands that form as rivers empty their water and sediments into another body of water such as an ocean, lake,  or another river. Deltas can also empty into land although this is less common.

A river moves more slowly as it nears its end. This causes sediment, solid material that has been carried downstream by the water  to fall to the river bottom.

The slowing of the river and the build up of sediment allows the river to break up from its single channel to several channels  forming a triangular flow at the mouth called a delta.