Answer:
The option that adds a participial phrase in the sentence is C) "Before the buzzer, the runner tripped on a shoelace dangling from her shoe."
Step-by-step explanation:
The participial phrase in this sentence is "dangling from her shoe". Participial phrases start with present or past participle. Present participle is formed by infinitive verbing (dangling).
Participial phrases act as adjectives in sentences, modifying a noun. In this sentence, the participial phrase is modifying the noun "shoelace".