Final answer:
The phrase "head under water" metaphorically represents Anne Frank's intense emotional state and limited perspective, emphasizing her struggle to consider others' viewpoints.
Step-by-step explanation:
The phrase "head under water" in the sentence from Anne Frank: The Diary of a Young Girl describes Anne's overwhelming emotional state and her limited perspective during her times of distress.
The figurative language suggests that she is submerged in her own emotions and thoughts, to the extent that she cannot see or consider the perspectives of others. This expression emphasizes the intensity of Anne's feelings and her difficulty in managing them, as well as her self-awareness of the resultant impact on those around her.