Achallenge that modern presidents face is

A challenge that modern presidents face is leading their political parties. For that reason, modern presidents use the constitutional power to appoint individuals who can trust in order to carry on their will. They also seek to include people who share their preferences in the government administrations. However, finding out and locating competent individuals to serve loyally in the presidents' administrations is one of the most difficult challenge a president may experience. Nowadays, political parties tend select those candidates who represent and identify with the most firmly-established ideological interests.

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.