Correct Answer: D
Explanation:
This sentence asks you to look for a word that describes how the ravens behave. The information after the comma restates and defines the meaning of the missing word. You are told that the ravens actively help one another. There is only one word among the choices that accurately describes this behavior – cooperatively.
| Ravens: | any of various large crows; esp., the largest crow (Corvus corax), with a straight, sharp beak, found in Europe, Asia, and North America
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| Warily: | in a wary manner; cautiously |
| Aggressive: | ready or willing to take issue or engage in direct action; militant |