Concept:
Prepositions of movement and place are used to describe the relationship between a subject and a destination. The choice of preposition depends on whether the subject is static (staying in one place) or in motion (moving from the outside to the inside).
Step 1: Distinguishing between "in" and "into".
While "in" describes a position inside a container or area (static), "into" is used to describe movement that results in being inside something. Because the verb in the sentence is "jump," there is a clear transition from the edge of the pool (outside) to the water (inside).
Step 2: Analyzing the direction of the action.
• On: Would imply jumping onto the surface (like a pool cover), not entering the water.
• To: Describes the direction toward a destination, but not the entry into it.
• At: Usually describes a target or a specific point, which is semantically incorrect for entering a pool.
Step 3: Concluding the motion.
When a person jumps and ends up inside the water, the correct preposition to show this entry into a three-dimensional space is "into".
Final Answer: Option C