Final answer:
Two siblings arguing over a toy is the situation that most clearly shows an example of squabbling.
Step-by-step explanation:
The situation that most clearly shows an example of squabbling is A. Two siblings arguing over a toy. Squabbling refers to a petty, argumentative behavior, often seen in situations where individuals have conflicting desires or interests. In this case, the two siblings are competing over the same toy, leading to a disagreement and squabbling.