1) Explanation

Let's break down the sentence to understand the context and the meaning required for the blank:
- "Although the couch had appeared imposing in the furniture store,..."
- "Although" sets up a contrast. "Imposing" means grand, impressive, or formidable. So, the couch seemed large and impressive in the store.
- "...once it was installed in the living room it seemed $\qquad$ by the grandeur of that room's high ceiling and sumptuous décor."
- The "grandeur" (splendor, impressiveness) of the room's "high ceiling" and "sumptuous décor" (luxurious furnishings) is the contrasting element.
- If the couch seemed "imposing" in the store, but the room itself is grand, then the couch would seem less imposing, smaller, or less significant in comparison. The blank needs words that convey this reduction in perceived size or importance.

Therefore, the blank needs words that mean made to seem smaller, less significant, or overshadowed.

Let's evaluate the given options:
- A. absconded: To leave hurriedly and secretly, typically to escape from custody or avoid arrest. This is irrelevant.
- B. minimized: To reduce (something, especially something undesirable) to the smallest possible amount or degree; to make (something) seem less important or significant. This perfectly fits the idea that the couch seemed smaller or less significant in the grand room.
- C. obviated: To remove a need or difficulty; to avoid or prevent. This is irrelevant.
- D. rarefied: (Of air or gas) of lower density; (of a subject or discussion) understood by only a small group of people with special knowledge. This is irrelevant.
- E. diminished: Made smaller or less. This is a strong synonym for "minimized" and perfectly fits the idea that the couch seemed less imposing or smaller in scale compared to the room.
- F. depicted: Represented or showed in a picture or story. This is irrelevant.

Conclusion:

The sentence describes a contrast where the couch, initially appearing large, seemed smaller or less significant when placed in a grand room. Both "minimized" and "diminished" accurately convey this reduction in perceived scale or importance.

The final answer is $\(\mathrm{B}, \mathrm{E}\)$.