You were incorrect in selecting "a unifying or dominant idea in a work of fiction" because that phrase describes a theme, not a conflict. A conflict specifically refers to the struggle or opposition between characters, ideas, or forces that creates tension within the narrative.
Correct Answer:
The phrase "a fight, battle, struggle, or strife" most clearly explains the nature of a conflict.
Simple Example:
In a classic story like "Romeo and Juliet" by William Shakespeare, the conflict primarily arises from the feud between the Montagues and the Capulets. Romeo and Juliet’s love for each other is thwarted by this ongoing struggle, creating tension and dramatic stakes in the plot. Their families' enmity represents a significant conflict that drives the narrative forward.