Which words in the sentence make up the participial phrase?
The bus driver, taking a break, stopped by the diner for lunch.
a. the bus driver
b. for lunch
c. stopped by the diner
d. taking a break
The participial phrase is the phrase with the participle, which is a verbal form that can function as an adjective, for example "reading" in " the reading girl".
Here it's "taking" as in Taking a break: the correct answer is d.