The lines "And it grew both day and night, / Till it bore an apple bright;" suggest that the speaker is experiencing a growth of anger that goes unacknowledged, ultimately leading to a culmination or manifestation of that emotion (symbolized by the "apple bright"). This indicates that the anger, rather than being contained or resolved, is flourishing and developing over time, even if the speaker is unaware of it.
Therefore, the best response is:
They show that the speaker does not realize the anger is flourishing.
Additionally, it could also imply that repressing anger causes it to develop and change into something tangible (the "apple"), but the first response captures the essence of the speaker's unawareness more directly.