Why do most coastal locations experience two high tides each day, approximately $12$ hours apart?

• A. Because the Sun's gravity causes the oceans to rise and fall twice daily, independent of the Moon's influence.
• B. Because Earth's rotation causes water to accumulate only on the side facing the Moon, leading to two high tides.
• C. Because the Earth's elliptical orbit around the Sun produces two high tides every $12$ hours.
• D. Because the gravitational pull of the Moon creates two tidal bulges on opposite sides of the Earth, resulting in two high tides as the Earth rotates through these bulges.

Answer: (D)

Verified step by step guidance

1. Understand that tides are primarily caused by the gravitational pull of the Moon on Earth's oceans.
2. Recognize that the Moon's gravity creates two tidal bulges on opposite sides of the Earth: one facing the Moon due to direct gravitational attraction, and one on the opposite side due to the inertia of the water.
3. As the Earth rotates once approximately every 24 hours, any coastal location passes through these two bulges, experiencing two high tides.
4. Note that the time between these two high tides is roughly 12 hours because the Earth rotates through both bulges in about half a day.
5. Conclude that the Sun's gravity and Earth's orbit have secondary effects, but the main reason for two high tides daily is the Moon's gravitational pull creating two tidal bulges.