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 to talk of an event that happened in the past and is followed by another event that also is in the past. This means that a past perfect tense talks of an event that is already done and finished sometime in the past.
In the given sentence, the speaker mentions "Alice is pleased with herself." The word "pleased" shows it is in the past. But the next sentence talks of an event that occurs before she was "pleased", meaning the second event led to the first event. This means that Alice's happiness was a result of the second sentence.
In this situation, the verb in the second sentence will be in the past perfect tense, as it describes an event that happened first.
Thus, the correct answer will be "had found".