The Imager for Mars Pathfinder (IMP) is an imaging system. It has two camera channels. Each channel has color capability. This is provided by a set of filters. It was developed by a team led by the University of Arizona. Scientists and engineers from around the world were a part of the team. The system has three parts: (1) It has a camera head. (2) It has an extendable mast with electronic cabling. (3) It has two plug-in electronic cards. Each card plugs into a slot within the spacecraft.

What is the main idea of the numerical list in the second paragraph?

A. the camera head of the imaging system
B. the extendable part of the imaging system
C. the electronic cabling in the imaging system
D. the two electronic cards in the imaging system
E. the three parts of the imaging system