Earth's magnetic field is created by the bar magnets reaction forces gravitational forces flow of electric charges

The correct option is;

Flow of electric charges

Explanation:

The movement of the enormous quantities of molten metals in the Earth's outer core generates electric current which travel several thousands of miles per hour due to the axial rotation of the Earth results in the metallic particles being lined up and generating very strong magnetic fields (due to dynamo effect) that extends all over the planet and into space.

regulation of gene expression. gene expression can be regulated by various cellular processes with the aim to control the amount and nature of the expressed genes. these regulatory proteins bind to dna and send signals that indirectly control the rate of gene expression

explanation:

false because ozone (o3) depletion does not cause global warming, but both of these environmental problems have a common cause: human activities that release pollutants into the atmosphere altering it.

global warming is caused primarily by putting too much carbon dioxide into the atmosphere when coal, oil, and natural gas are burned to generate electricity or to run our cars.

explanation: