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We need to find explanatory and response variables for given study.

In this study, infants are followed through their sixth year of school to see if the amount of time they spend in child care has an impact on their personalities, such as if they are more assertive, disobedient, or aggressive.
As a result, we may argue that time spent in child care is an independent variable, whereas violence at an older age is a dependent variable because it is reliant on time spent.
As a result, the time spent in child care as a newborn is an explanatory variable, while violence at a later age is a response variable.

We need to find is this an observational study or an experiment.

The children were observed throughout their sixth year of school in this study, but the researchers had no influence over the youngsters and hence no treatments were administered to them.
As a result, the researchers did not assign therapies to the children, making this an observational study.

We need to find that does this study show that child care makes children more aggressive.

We learn that the study is an observational study in portion (b).
Because the outcome could be influenced by the hidden variables, it is impossible to say if child care is the source of the infants' aggressiveness.
The temperament of the parents could be a hidden variable, as children tend to have the same temperament as their parents, and the temperament of the parents could impact their decision to leave the child in child care.
It is preferable to conduct an experiment rather than an observational research since there is less likelihood of the lurking variable influencing the outcome.