The statement '(a) there are billions of galaxies in a galaxy cluster' accurately describes a relationship between two parts of the universe.
The solar system can be defined as a group of billions of galaxies that form a cluster due to gravitational forces that maintain all these celestial bodies linked together. This system contain our Sun.
In conclusion, the statement '(a) there are billions of galaxies in a galaxy cluster' accurately describes a relationship between two parts of the universe.
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