How does the national government improve public health?

it educates the public about healthy lifestyles and asks people to pursue them.

it takes national-level issues to international organizations to resolve them.

it declares standards for public health and writes policies to achieve those standards

Explanation:

The third option is the best choice, because national government cannot just rely on people hoping that they will care themselves and develop healthy lifestyles. Similarly, having international organizations to improve public health is to just avoid the problem and pass it to another institution, that is to elude the responsibility.

Lastly, declaring standards for public health will set a planned specifically set rules that organizations have to follow all over the nation in order to achieve public health improvement.