Answer:
Confident.
Step-by-step explanation:
The phrases watchful eye, strong form, and steady strides all give the impression that the police officer is confident. The other options are not as fitting. The word "sympathetic" would not be an attitude we would attribute to a police officer with a watchful eye and a strong form. Furthermore, the phrases do not directly suggest that he is "angry." Someone watchful, strong, and steady could be calm. The last option, "uncertain" also doesn't make sense. The police officer is described as being steady. Someone steady is certain of his/her standing. So, by process of elimination, we can rule out sympathetic, angry, and uncertain and choose the most reasonable answer; confident.