Final answer:
The repetition of the word 'heart' in Walt Whitman's 'O Captain! My Captain!' reflects the poet's disturbed state of mind and conveys his horror at the death of his captain. Therefore, the correct option is A.
Step-by-step explanation:
Two effects of the repetition of the word 'heart' in Walt Whitman's 'O Captain! My Captain!' are:
- It reflects the poet's disturbed and agitated state of mind. The repetition of 'heart' emphasizes the emotional turmoil and grief the poet feels at the death of his captain.
- It conveys the poet's horror at the death of his captain. The repetition of 'heart' expresses the deep sense of loss and sadness the poet experiences.