Final answer:
The correct completion for the sentence 'The sight of death is as a bell that warns my old age to a supple' is 'supple tune', reflecting a poetic approach to the theme of death and its relation to life's progression.
Step-by-step explanation:
The line "The sight of death is as a bell that warns my old age to a supple" suggests a contemplation of aging and mortality. The correct completion for this sentence is "supple tune" which reflects a harmony or order to the progression towards death and the inherent poetry found in the contemplation of life's end.
This thematic exploration is common in literature, where authors often use the concept of death to underscore the fragility of life and the importance of each moment. The representation of death as a dance or a song is a motif seen in various texts, equating the finality of life with a performance or a composed piece of music.
Looking at the context and the options provided, option d) tune fits best both thematically and poetically within the literary excerpts provided.