Which of the following causes high and low tides on Earth?
(a)The moon's gravitational pull on Earth causes water to bulge on two sides of the Earth.
(b) Water swells when tsunamis occur in two areas of Earth at the same time.
(c)The Earth's rotation is so fast, water will swell and shrink twice a day.
(d)The Earth is tilted on an axis, causing water to spread unevenly throughout the planet.