Why do rivers flow to the ocean?

Answer: Gravity pulls water downhill

Ocean pulls water magnetically — Wrong. The ocean doesn't have magnetic properties that pull water. Water is not magnetic. Rivers flow because of gravity - they follow the path of least resistance downhill, and oceans are at the lowest elevation.

Gravity pulls water downhill ✓ — Correct! Water always flows downhill due to gravity, following the path of least resistance. Rivers start at high elevations (mountains, hills) and flow toward the lowest point - usually the ocean. The land surface naturally slopes toward the sea. Rivers carve valleys over time, creating channels that guide the flow. All rivers eventually reach the ocean or an inland lake/sea at a lower elevation!

Rivers follow underground tunnels — Wrong. Rivers don't follow underground tunnels - they flow on the surface along channels they've carved through erosion. Groundwater can flow underground, but rivers are surface water flowing downhill due to gravity, creating their own paths over geological time.