In which stage does a person develop life skills and learn to take initiative?

a. infancy

b. childhood

c. adolescence

d. adulthood

The best answer is adolescence. In infancy the person is not independent yet, so they can't work on their life skills or initiative: they still depend on their parents. This is similar in childhood although to a lesser degree.

In adulthood these skills are already required so it's too late to try to develop them.