3.Annoying me into a rude awakening, the alarm continued to buzz loudly in my ear.
A participial phrase begins with a participle. A participle is a verb used as an adjective. Sentence 2 does not have a participial phrase. An infinitive phrase starts with an infinitive. An infinitive is a verb written in its to + verb form. Sentences 2 and 3 are the only sentences with an infinitive. In sentence 2 the participial phrase is "Annoying me into a rude awakening". It describes the alarm. The infinitive phrase is "to buzz loudly in my ear."