In the sentence 'By calling every hour, my mother received Jamie's call', the type of error in the sentence is called, Dangling Construction. A dangling clause or sentence, consists of a group of words wherein it does not clearly state what word or words it really describes.
The underlined pronoun <em>who </em>is used as a D) subject in this sentence. The subject is the doer of the action, the one who left mittens on the ground, in this case.
