Levinson placed the greatest weight on the five periods of adulthood. what are these five periods?

The five periods of stress in the period of adulthood of a person are as follows:

1.Early period of transition to adulthood

2. Entering adulthood

3.Period of transition during the age of 30 years

4.Period for settle down

5.Transition of midlife

These are the periods described by Levison, which are faced by adults.

b. the carbon cycle ensures living things have a source of hydrogen

i'm thinking (a) to keep sand in place; ////////////

explanation: a sand fence or sandbreak, like a snow fence, is used to force windblown, drifting sand to accumulate in a desired place. sand fences are employed to control erosion, sand dune stabilization, keep sand off roadways, and to recruit new material in desert areas.