Complex sentence: The Petersen graph is the unique 5-cage (it is the smallest cubic graph of girth 5), the Heawood graph is the unique 6-cage, and the Tutte eight cage is the unique 8-cage.
Split into simpler sentences: The Petersen graph is the unique 5-cage (it is the smallest cubic graph of girth 5). The Heawood graph is the unique 6-cage, and the Tutte eight cage is the unique 8-cage.