What causes tides on Earth?

• A. Ocean currents caused by wind
• B. Oceanic movements due to Moon's gravitational pull and Earth's rotation
• C. Tides due to Sun only
• D. Local rainfall patterns

Answer: (B)

Tides are created by gravity from celestial bodies acting on Earth’s oceans, and their regular rise and fall is shaped by how Earth spins. The Moon’s gravity pulls on the oceans, creating a bulge on the side of Earth closest to the Moon and another on the opposite side. As Earth rotates, any given coastline moves into and out of these bulges, producing the high and low tides you experience. The Sun also pulls on the oceans, adding to the Moon’s effect, though its gravity is weaker for tides because the Sun is so far away. When the Sun, Moon, and Earth align, tides are especially strong (spring tides); when they’re at right angles, tides are weaker (neap tides). Wind-driven currents and rainfall don’t set up the regular tidal pattern, so the best description is the gravitational influence of the Moon (and the Sun) combined with Earth’s rotation.