Please help me in this.

Manifest Destiny was a theory that argued that America had a religiously supported right and push to control all of the land between the Atlantic and the Pacific Oceans. Therefore, this philosophy was essential in pushing the frontier farther west towards the Pacific Ocean.  

Explanation:

So my high schooler answer would be manifest destiny means like, you’ll do anything to achieve a goal or a task because it’s your “manifest destiny” and for the westward expansion part I’d say is because of the Gold Rush and the Oregon Trail.

Explanation: hopefully this somewhat helps

what are local authorities doing to fix the problem

explanation:

what are local authorities doing to fix the problem

the answer is mass marketing.