MTTC 103 Elementary Practice Exam 2026 – All-in-One Guide for Comprehensive Exam Success

The primary reason that the highest tides occur during a full or new moon is that the sun, moon, and Earth align in a straight line. This alignment results in the combined gravitational forces of the sun and the moon acting in the same direction, exerting a stronger pull on the Earth's waters.

During the full moon, the Earth is between the moon and the sun, allowing the gravitational forces to work together to enhance tidal effects. Similarly, during a new moon, the moon is positioned between the Earth and the sun, leading to the same additive effect on tides. This phenomenon is known as "spring tides," where the tidal range— the difference between high tide and low tide— is at its maximum.

Other options are less relevant because they do not directly relate to the gravitational pull affecting tides during full and new moons. The positioning of the Earth and the moon in relation to the sun is the crucial factor driving these extreme tidal conditions.