Final answer:
The third incident of Spitz's attempts to attack or harm adds depth to Spitz's character, increases suspense, and may also emphasize Buck's survival skills in 'The Call of the Wild'.
Step-by-step explanation:
The inclusion of the third incident of Spitz trying to attack or harm in Jack London's 'The Call of the Wild' serves multiple narrative purposes. The third incident of Spitz's attempts to attack or harm adds depth to Spitz's character, increases suspense, and may also emphasize Buck's survival skills in 'The Call of the Wild'.
Primarily, it develops Spitz's character, showcasing his aggressiveness and establishing him as an antagonist. Secondly, it creates suspense in the story, as the repeated conflicts between Spitz and Buck heighten the reader's anticipation of an eventual confrontation.
Lastly, it may also serve to highlight Buck's survival skills and his adaptability to the harsh conditions of the Klondike. Similarly, in other literature like Twain's work, conflict drives plot development and character growth, while Norris's 'McTeague' uses environmental forces to shape the protagonist’s descent.