The answer would be social environment. Claire of course lost the weight because of her hard work but the encouragement from her friends definitely helped motivate her.
The answer here is B they are each made of matter. some are compounds, and some are elements they all contain Atoms this is because Silver and Oxygen are elements while Carbon Dioxide and Water are compounds. Although you do not have the choices down, I have come across this question before.
4-6 months, infancy because the child can only really hold his head up. The mother is talking about her baby.
The control group is usually the group in which none of their variables are changed. This group is used in order to compare it with the outcomes of the other groups.