Explanation
The correct option to fill in the blanks is:
B) was
Explanation: In this sentence, "the chief, with all his men" acts as a singular subject, as it refers to a collective group functioning as a unit. Therefore, the correct verb form to use is the singular "was" to agree with the subject. Option A) were, Option C) have been, and Option D) are are all incorrect because they are plural verb forms that do not agree with the singular subject