Final answer:
The phrase "the coming harvest" in the poem represents C) a metaphorical representation of the results or rewards of one's efforts, drawing from the thematic exploration of time, work, and outcome.
Step-by-step explanation:
The phrase "the coming harvest" in line 20 of the poem most closely refers to C) A metaphorical representation of the results or rewards of one's efforts. This interpretation is supported by the context within the poem and similar texts, where the harvest season is often used as a metaphor for the fruits of labor or the outcome of one's work.
Although option B, the literal act of harvesting crops, is also a plausible interpretation since the text does describe actual agricultural practices, the metaphoric meaning is reinforced through the poem's overall thematic exploration of time, effort, and reward.