Final answer:
The underlined phrase in the sentence is a participial phrase, which functions as an adjective describing Alisha being distracted by her father's snoring.
Step-by-step explanation:
In the sentence 'Distracted by her father's snoring, Alisha decided to study for her test in the kitchen', the underlined phrase is a participial phrase. A participial phrase is a verb form ending in -ing or -ed (past participle) that functions as an adjective. In this case, the phrase 'Distracted by her father's snoring' describes the state of Alisha being distracted by her father's snoring.