Answer: A) He lists his personal involvement in climate change work.
Explanation: In the given excerpt from the Nobel Lecture by Al Gore, we can see that he describes his journey in the subject of climate change, he says that he spoke at the "Earth Summit" in Rio de Janeiro, then in Kyoto and then in Bali. From the given options, the one that represents how Gore establishes his credibility on the sobject of global warming is the correpsonding to option A: He lists his personal involvement in climate change work.
