Which of the Following Is a Complicating Factor That Makes

Which of the following is a complicating factor that makes subscription counting an inadequate way of determining a magazine's readership? 

A)  Magazine subscriptions are collected through a variety of intermediaries, making it difficult to obtain accurate lists of who subscribes to what magazines. 
B)  Magazines often are purchased from newsstands, supermarkets, and other retail outlets rather than through subscriptions, thus completely eliminating knowledge of who purchases what magazines. 
C)  Magazines that are available in public locations (i.e., doctors' offices, beauty salons) are read by numerous people and not just the subscriber. 
D)  Individual magazines subscribers share issues with other people. 
E)  All of these are correct.