Question

What is the best way to combine the sentences below using a participle phrase?
Val diligently strove to do her best. She knew that perfection was necessary.
A. Val diligently strove to do her best knowing that perfection was necessary.
B. Knowing that perfection was necessary, Val diligently strove to do her best.
C. Val knew that perfection was necessary; she diligently strove to do her best.

Answer 1

Although A and B are really similar, I would say the correct answer is B, because it seems right to have a comma somewhere in the sentence, something which the first example is missing. 

Answer 2

B. A participle phrase is a verbal ending in -ing (present) or -ed, -en, -d, -t, -n, or -ne (past) that functions as an adjective, modifying a noun or pronoun. The word "knowing" is the participle because it acts as an adjective to modify the pronoun "Val".