At the paper mill, what is used to soften the small wood chips in the big tank?

The correct answer is B: steam.

At a paper mill, steam is used to soften small wood chips in a big tank during the pulping process. The heat and moisture from the steam help break down the lignin in the wood, making it easier to separate the cellulose fibers that are used to produce paper. If you have any more questions or need further clarification, feel free to ask!