A phrase is commonly defined as a unit or group of words that form part of a clause or a sentence. Unlike clauses, phrases do not contain a subject and verb therefore, they cannot convey a complete thought or idea.
Bearing in mind the stated above, it could be said that in the sentence "<em>Christine blew out the candles on the cake and opened her presents",</em> the phrase is the option a.on the cake since this option not only does not contain a subject and verb but also does not convey a complete thought or idea.
