You are writing a report on whether global warming really exists. Which of the following resources would be the most scientifically reliable?

an article containing documented experiments and data

a newspaper article quoting leaders of several countries

a website with articles posted by people around the world

an article containing a poll taken of students at leading universities

The appropriate answer is a. an article containing documented experiments and data. All other options are sources that can have unreliable data. Newspaper articles, polls and websites can have individual biases reported in the text. Credible data is most likely to come from peer reviewed articles that publish data gathered from years of conducting controlled experiments that will provide acurate and reliable data.

The article containing documented experiments and data. It's presumably the only one with information from experts who conducted actual experiments.