The sentence that contains a boldface infinitive is D. Lisa wants TO GO.
It is easy to spot an infinitive - it is usually a combination of the word TO plus a verb.
A and C are incorrect because those are not infinitives, but rather prepositional phrases. B is incorrect because it is an infinitival phrase, rather than a single infinitive.
The answer is a. It's an adjective phrase because it helps describes the window.
A.
It’s assigning a human action to an inanimate thing.
