直面

長引く不況により、多くの企業が経営不振に ___ している。

The correct answer is **直面 (ちょくめん)**. The phrase "～に直面する" means 'to face' or 'to confront' a situation, often a difficult one. This perfectly fits the context of many companies 'facing' business stagnation due to a prolonged recession. **進行 (しんこう)** means 'progress' or 'advance.' "経営不振に進行する" is grammatically incorrect; one would say "病気が進行する" (a disease progresses) or "計画が進行する" (a plan progresses), but not with a difficult situation as the direct object with 'に'. **対立 (たいりつ)** means 'confrontation' or 'opposition.' Companies 'face' stagnation, they don't 'confront' it as an opponent with 'に'. **継続 (けいぞく)** means 'continuation.' "経営不振に継続する" is grammatically incorrect; one would say "不況が継続する" (the recession continues), or "経営不振が継続している" (business stagnation is continuing). The structure with "に" doesn't fit.

正解は**直面**です。「～に直面する」は、困難な状況や問題に面と向かうことを意味し、「経営不振」という状況にぴたりと合います。 「進行」や「継続」は文法的に「経営不振に～」の形に合いません。「対立」は意見や勢力が衝突する際に使う言葉で、状況に使うのは不自然です。