Read an excerpt from the nobel lecture by al gore: fifteen years ago, i made that case at the "earth summit" in rio de janeiro. ten years ago, i presented it in kyoto. this week, i will urge the delegates in bali to adopt a bold mandate for a treaty that establishes a universal global cap on emissions and uses the market in emissions trading to efficiently allocate resources to the most effective opportunities for speedy reductions. how does gore establish his credibility on the subject of global warming in this excerpt? a. he lists his personal involvement in climate change work. b. he shows the logic of his worldwide travels. c. he gives an emotional plea about worldwide deficiencies. d. he appeals to an international crowd.