The Earth is divided into 24 standard time zones.  Each of these time zones covers approximately 15 degrees of longitude.  These time zones are based primarily on which of the following phenomena?Group of answer choicesThe locations of natural boundaries such as mountains and rivers.Earth’s rotation on its axisThe movement of the sun around Earth.The movement of the moon around Earth.

The Earth's time zones are primarily based on Earth’s rotation on its axis. Here's why:

1. The Earth rotates 360 degrees in about 24 hours. This means it rotates about 15 degrees every hour.

2. To make time measurement consistent and manageable, the world is divided into 24 standard time zones. Each of these time zones covers approximately 15 degrees of longitude, which is the distance the Earth rotates in one hour.

3. Therefore, the time in each zone is based on the position of the Earth in its rotation at any given moment. This is why when it's noon in one time zone, it's 1 p.m. in the time zone immediately to the east (where the Earth has rotated a further 15 degrees), and 11 a.m. in the time zone immediately to the west (where the Earth has yet to rotate the next 15 degrees).

4. So, the time zones are not based on the locations of natural boundaries such as mountains and rivers, nor the movement of the sun or the moon around Earth. They are based on Earth’s rotation on its axis.