By the time he/she was 17 years of age, had already written the octet for strings, op.20. a. wolfgang amadeus mozart b. felix mendelssohn c. joseph haydn d. fanny mendelssohn hensel

Where’s the paragraph? ?

Cis the correct answer

What u have here is a dangling do not have a subject that goes with ur verb. you do not have a " doer " for the actionhaving read the children a bedtime story, the house was shut down for the night.  so who read the children the story ? it wasn't the house. so we have to add a doer of the action to revise this sentence.having read the children a bedtime story, jill shut the house down for the night. < == this is the revised sentence. 

Iwould have to agree mghdm