Answer:
Collect some data about the distribution of the explosive.
Step-by-step explanation:
Following 9.06's Scientific Method Lab, we can see that what Adams has done is ask a question: who set the explosive?
The next step of the scientific method would be conducting research, followed then by forming a hypothesis. So the answer is collect some data about the distribution of the explosive, as that falls under conducting research.
(I'm literally taking the test right now, so if it's wrong, then bleh. I tried.)