from ,begin bold,The First Laugh,end bold,

in the life of every baby there is a continuous succession of first impressions and adventures. The first tooth, the first crawl, the first step, the first word, each mark a milestone in the child's career. But more interesting than any of these is the first laugh—the first genuine, sustained, prolonged, whole-hearted laugh. If it is a tinkling, bubbling, echoing laugh, it sends its merry waves in all directions—the kind that brings smiles to sober faces.

(from "The First Laugh" by Reuben F. Place)

Question
This sentence is from the passage.



"The first tooth, the first crawl, the first step, the first word, each mark a ,begin emphasis,milestone,end emphasis, in the child's career."



What does the word ,begin emphasis,milestone,end emphasis, mean in the passage?

Answer options with 4 options
1.
valuable lesson

2.
worthwhile goal

3.
important event

4.
shared challenge

3. important event