What does the author mean by saying put the earth at the top of their agenda in the begi

What does the author mean by saying "put the earth at the top of their agenda" in the beginning sentence of the passage？

A．The author intends to discuss the issue of global warming with top government leaders.

B．The author lays stress on the research of the climate of the earth.

C．The author attaches paramount importance to the protection of the earth"s environment.

D．The author considers the relation between automating and environmental pollution.

请帮忙给出正确答案和分析，谢谢！