Option D Gather more evidence before reaching the conclusion
Explanation:
Several factors might influence the scientists to disagree. For example, one of the reasons could be the safety of the bags. The first one might argue that plastic bags pollute the environment. The second one might argue that plastic bags are not harmful at all.
The other scientists may argue that plastic bags are non-biodegradable and therefore pollute the environment and cause many problems. The other one may argue that plastic bags are now biodegradable. So, the best way is to gather evidence before establishing the correct point.