Answer:
a. The study of how we grow and change from conception to death.
Explanation:
Lifespan development refers to the development process which begins from the time of conception to the time of death. It deals from a wide range of understanding of emotional, physiological, cognitive and social changes that humans undergo in their life. It is considered as the development which covers the entire life of an individual.
1.make an observation
2.research
3.form a question
4.from a hypothesis
5.conduct an experiment
6.record your results
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The answer to that would be 4000 pounds :)