Which statement is true?

time zones are exactly 15° apart around earth.

time zone borders on land may curve to keep regions together.

there are 12 time zones around earth.

each country or nation has only one time zone.

The first one

Explanation:

Each time zone is 15° apart longitude wide the distance between the zones,

greatest at the equator and shrinks to zero at the poles, due to the curvature of Earth.

answer; gravity pulls glaciers down hill and as glaciers flow it pick up rocks and soil;

it is very hard for the climatologists to precisely predict how will the global temperatures be changing so there's lots of models, some of which differ significantly, this is due to multiple factors, and probably the most important is the human activity.

humans have been a key factor in climate change around the globe since the start of the industrial revolution, and in the past few decades the consequences are becoming more obvious. there's lots of emission of pollutants in the atmosphere as well as changing the environment on the surface itself, so it's really hard to predict how will that go in the future because there's some countries that are reducing the damage and are going towards green energy, while others are stubbornly continuing with pollution and damages to the environment.