Design a device that will knock a block of wood a distance of 5 meters. This was the challenge in science class. Ben and Sam designed a pendulum to move the wood block. Their first design moved the block about 1.5 meters. They rebuilt their pendulum and changed the mass of the pendulum bob. After the changes, the boys knocked the block of wood 4 meters, 6 meters, and finally 8 meters. The average distance the block moved after the final changes to the pendulum was 6 meters. The boys won the design challenge.
Changing the pendulum design after the first trial was an example of to solve the problem presented by the teacher.

A) designing the model
B) evaluating the model
C) identifying the problem
D) doing research on the problem