Final answer:
The correct verb form is 'está' when completing the sentence.
Step-by-step explanation:
The correct verb form that best completes the sentence is está. This is because está is the third person singular form of the verb estar (to be), which matches with the singular noun la figura del Ángel Caído. The phrase justo al lado del estanque provides additional information about the location of the figure.
Learn more about Verb forms in Spanish