Before sometimes, the monkey jumped . . . . . . the river.

Solution (By Examveda Team)

The sentence describes the monkey's movement. The preposition "into" indicates movement from the outside to the inside of something. In this context, it shows the monkey moving from a position outside the river to a position inside the river (presumably by jumping in).

Why other options are incorrect:
A (on): "On" indicates a position on the surface of something. The monkey didn't jump onto the surface of the river; it jumped into the water.
C (near): "Near" indicates proximity. This doesn't describe the monkey's action (jumping) or its location after the jump. The monkey jumped *into* the river, not just near it.
D (upon): "Upon" is a more formal synonym of "on," and suffers from the same problem as "on." It implies a position on the surface, not an entry into the river.

Therefore, only "into" accurately reflects the action and location described in the sentence.