- "Adulthood is a stage in the life cycle process " is not a useful statement here

- If something is a source of something else then that something else comes from that something
- The sun is the source of energy for life on earth
- So, energy on earth comes from the sun

- Energy on earth comes from the sun
- Living things all require energy for survival
- Hence, living things require energy from the sun for survival

- Living things require energy from the sun for survival
- If a living thing requires something for survival then that living thing depends on that something
- Therefore, living things depend on energy from the sun

Therefore, living things depend on energy from the sun
Living things depend on energy from
- Living things all require energy for survival 
- Adulthood is a stage in the life cycle process 
- If something is a source of something else then that something else comes from that something 
- If a living thing requires something for survival then that living thing depends on that something 
- The sun is the source of energy for life on earth