The tone of the testimony in Document 4 is one of...
passion
indifference
anger
astonishment

The tone that can be detected from the witness testifying in Document 4 was that of indifference.
A person is said to be indifferent in tone when they simply recite a story in neutral terms. They basically state facts without adding emotions.
The SS guard in this testimony conveyed no emotion as he described the way they killed the 30 - 40 Jewish women by gassing them.
In conclusion, option B is correct.
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