The participial phrase in the sentence is C. INSTRUCTED WITH A TEACHER'S CARE.
Participial phrase always starts with a participle. The participle may be present or past participle. Present participle ends with -ing. Past participles end with -d or -ed.
In the above sentence, the participial phrase started with a past participle, Instructed. Always remember, participial phrases serve as adjectives in the sentence. It modifies students in the sentence.
