At the beginning of the twenty-first century, some people placed signs with crudely painted skeletons holding cell phones near roadways, usually facing freeway ramps. These signs indicated disapproval of using cell phones while driving, a practice some states have now made illegal. As a result of these laws an informal has become a law.

The answer is norm.

Refer below for the explanation.

Explanation:

Therefore,

At the beginning of the twenty-first century, some people placed signs with crudely painted skeletons holding cell phones near roadways, usually facing freeway ramps. These signs indicated disapproval of using cell phones while driving, a practice some states have now made illegal. As a result of these laws an informal norm has become a law.

Norm is a pattern or a general rule.

answer; i believe that the correct answer is rapid and subsequently slow down;

the first settlements began along the huang river because of the importance of the huang river in the beginning of china. it goes back to the story, “the tale of emperor yu”, which references the tale of the great flood, which was caused by the huang river and was believed to create and influence china’s making.