Explanation:

The correct answer is "had reserved" because it indicates that the action of reserving the hotel room occurred before the action of traveling to Lisbon. The past perfect tense is used to express an action that happened before another action in the past.

Verb Tenses:

In this sentence, we are dealing with two past actions - reserving the hotel room and traveling to Lisbon. To indicate the sequence of these actions, we need to use the appropriate verb tenses.

1. Past Perfect: The past perfect tense is formed by using the auxiliary verb "had" followed by the past participle of the main verb. It is used to express an action that happened before another action in the past.

2. Simple Past: The simple past tense is used to express a completed action in the past.

Sequence of Actions:

1. Reserving the hotel room: This action happened before traveling to Lisbon. Therefore, the past perfect tense is used to indicate that the reservation was made before the trip.

2. Traveling to Lisbon: This action happened after the hotel room was reserved. The simple past tense is used to express the completed action of traveling.

Sentence Construction:

The sentence is constructed as follows:

"Before she traveled to Lisbon, she had reserved the hotel room."

The phrase "Before she traveled to Lisbon" indicates the time frame in which the action of reserving the hotel room occurred. The past perfect tense "had reserved" is used to show that the reservation happened before the action of traveling.

Summary:

In summary, the correct answer "had reserved" indicates that the hotel room was reserved before the trip to Lisbon. The past perfect tense is used to express this sequence of actions, with the action of reserving the room happening before the action of traveling.