Professor Ober carefully monitors and records the behaviors of children on school playgrounds in order to track the development of their physical skills. Professor Ober is most clearly engaged in

naturalistic observation

Explanation:

In naturalistic observation, researchers will gather data by directly  observing the subjects in their natural habitat without making any intervention.

This is what Professor Ober is doing.

Professor Ober wants to collect a data about development of their physical skills among children. This means that the children are his research subjects.

To collect his data, professor Ober observed the children in the playground (which is  the children's natural habitat). He also did not told the children to do anything , he just quietly observe and let the children do what  they usually do. (not making any intervention)

find out yourself so

this statement is true.

forests are public goods, available for everybody. when usage of such a good becomes interesting for consumers and its usage increases, there can be a risk of overexploitation. it is a non rival good therefore, if one person consumes the good it does not reduce the availability for subsequent consumers.

these caracteristics require the establishment of measures in order to prevent the destruction of a commonly owned space, for example, to restrict the amount of people that have access to the same time.