The united states gave much attention to environmental issues in the 1980s and 1990s. preservation efforts have included:

care of endangered species
maintenance of lands and parks
purification of the air
all of the above

the correct statement is letter a.   according to the mandate of heaven, kings were considered godlike beings, so they could do as they .

the mandate of heaven is a chinese political and religious ideology used since ancient times to justify the rule of the king or emperor of china, that has been in place since the zhou until the dynasty system ended. it has been created to justify the zhou as the main power of the region. in order to keep harmony, the ruler has to make what he wants and what people want. he had to make good choices to satisfy the people and then they will be happy and keep you in power.