Answer: Less than a decade ago, the HSUS began pursuing global work through an affiliate [Humane Society International].
Explanation:
Square brackets are used either to clarify the information that was already given or, more commonly, to add new information. As for Option A, "global work" does not need any further explanation. In option C, the time period is already given - "less than a decade", and it does not need to be precisely determined. In Option D, the acronym "HSUS" was already explained at the beginning of the paragraph. Therefore, the correct answer is Option B. The use of brackets, in this case, provides additional information about an affiliate mentioned in the sentence.