Answer:
Alice felt very pleased with herself. She had found what she was looking for.
Step-by-step explanation:
The past perfect tense is used when we talk of an event that has happened in the past, sometime back, and completed before another past event. This means that the event happened before another event, and both events were in the past.
Also, the past perfect is used to talk of an event that happened first, and that event led to another event. This means that both events are in the past but we will use the past perfect for the event that happened first. And the construction of a past perfect tense is the use of "had+ past participle".
Thus, the correct answer in the given sentence will be "had found".