Step 1: Understanding the context.
The sentence describes a slow-moving river, and it compares the river’s flow to blood circulation in a dying man. The focus is on slowness, weakness, and lethargy. Thus, we need words that suggest a slow and unenergetic state.
Step 2: Analyzing the options.
(A) sluggish, briskly: "Sluggish" works well to describe slow movement, but "briskly" is contradictory as it suggests speed and energy. This combination doesn’t fit the context.
(B) indolent, undignified: "Indolent" means lazy or lacking energy, which fits the description of slow movement like the circulation in a dying man. "Undignified" suggests a loss of grace or respect, aligning well with the idea of decay or a weakening state. This pair best fits the metaphor.
(C) tardy, belated: These words imply being late, but they don't relate directly to the movement of the river or its comparison to a dying man's circulation. They don't quite match the context of the sentence.
(D) active, lively: These words suggest vigor and energy, which contradicts the description of a dying man’s circulation and the slow movement of the river. They are not fitting choices.
Step 3: Conclusion.
The correct answer is (B) indolent, undignified, as these words accurately describe the weak and slow movement of the river, similar to the blood circulation in a dying man.