Here's a problem to solve: A group of students have decided that the amount of electricity used by the school should be reduced. The students want to develop a plan to solve this problem. What should the group do first?

Among the 4 following options, which is the correct answer?

- A: determine what materials should be used to implement the plan
 
- B: conduct research on energy conservation to form the plan
 
- C: improve the design of the plan
 
- D: test the validity of the plan
 