Final answer:
The novel's title, The Grapes of Wrath, symbolizes the strength of community in the face of adversity and the need for social unity. This is portrayed through the Joad family's journey and their realization of the importance of joining a larger social movement.
Step-by-step explanation:
The significance of the novel's title, The Grapes of Wrath, is best explained by the greater lesson learned in the story - the strength of community in the face of individual adversity. The Joad family's exodus from their farm to California represents their journey towards realizing the need to join a larger social movement-communism-dedicated to bettering the lives of all people. This theme is reinforced by Tom Joad's statement that every individual is a piece of a larger soul that belongs to everyone.