Final answer:
The passage suggesting that ravens watch and cackle as crows try to eat pebbles is indicative of a sense of humor, contrasting with other options that show typical bird responses. Therefore, the correct Option is D).
Step-by-step explanation:
The evidence from the passage that best suggests that ravens have a sense of humor is the following: "The ravens watch and cackle as the crows try to eat pebbles." This behavior demonstrates amusement at the expense of another species, which could be interpreted as a form of humor.
Unlike other options provided that show defensive or common behavior, such as squawking due to intrusion or biting in response to being provoked, the act of watching and cackling shows a more complex, possibly playful interaction with the environment that aligns with behaviors often associated with a sense of humor.