Final answer:
The word that best identifies the speaker's tone is 'Indignant'.
Step-by-step explanation:
The word that best identifies the speaker's tone is D. Indignant. Indignant means feeling or showing anger or annoyance at what is perceived as unfair treatment. In the given context, the speaker's disapproval and negative attitude towards the untrained, unrestrained dog's actions indicate an indignant tone.