Final answer:
The best example of a statement of subject is option a) 'The cat chased the mouse.'
Step-by-step explanation:
The best example of a statement of subject is option a) "The cat chased the mouse."
In this sentence, "cat" is the subject because it is the entity performing the action of chasing. The verb "chased" indicates the action, and the noun phrase "the mouse" acts as the object of the action.
Other options b), c), and d) are also complete sentences, but they have different subjects and verbs that describe different actions.