Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.

• Climate change caused by human activity is the main reason for the increase in fires over the past 30 years.
• While human activity is definitely considered a factor, foresters are still debating whether climate plays a role in the recent increase in fires.
• For complicated reasons, over the past 30 years there has been an increase in the number of fires that take place during hot, dry summers.
• Both climate change and human activities are responsible for the recent increase in forest fires, although the contributions of those factors are still not agreed on.

This is a multiple choice.