单选题
The only solution to rubbish problem for a nation which now spends more on wrapping food than it pays farmers to produce it, is recovering______the packaging materials for commer cial as well as for conservation reasons.
【正确答案】
C
【答案解析】on a large scale“大规模地”；on sale“出售”；on the spot“当场；在现场”，用在句中语义不明确；on all sides“四面八方”，也不合适。