Determine the relationship between the two ideas that are connected by the missing transition. The idea before the transition is that Attila's grave was a tempting target for friends and enemies alike. The idea after the transition is that Attila's grave was safeguarded by killing everyone involved with the burial to keep its location secret. Either a sequential or cause-and-effect transition could work here. This is a good question to use elimination on the answer choices.
Choice (A) may be tempting, but it's incorrect; "finally" is a sequential transition that comes at the end of three or more events in a sequence. Although the sequence of Attila's threefold coffins is discussed earlier in the text, it is unrelated to the discussion of keeping his grave safe. There are only two events in this sequence-the grave was at risk, and then it was safeguarded-so "finally" does not suit the context. Eliminate (A). Choice (B), "consequently," is a cause-and-effect transition that fits the context; the grave was at risk, and then those who knew its location were killed. On test day, select (B) with confidence and move on to the next question, but the sake of review: (C), "moreover," can be eliminated because it is a continuation transition; (D), "lastly," can be eliminated for the same reasoning as (A).