Which of the following is a correct sentence featuring an infinitive?

The sentence "I hope to pass my English test" successfully features an infinitive. An infinitive is the base form of a verb usually preceded by "to," and in this case, "to pass" functions as an infinitive. It expresses an intention or aspiration related to the subject "I," indicating what the speaker hopes to achieve.

The other choices either are not complete sentences or do not effectively demonstrate the use of an infinitive in context. For instance, "To climb the tallest mountain in the state" and "To study for the exam" are both phrases that start with infinitives but lack a subject and a verb, making them incomplete sentences. The phrase "Mr. Valdez to finish his work on time" is also incomplete as it does not form a coherent sentence. Only the second option integrates a subject and a verb, thereby constructing a complete thought that illustrates proper sentence structure with an infinitive.