Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks. 

The invention of the mobile phone has undoubtedly revolutionized the way people communicate and influenced every aspect of our lives. The issue is whether this technological innovation has (26) ______ more harm than good. In order to answer the question, we must first turn to the types of consumers. Presumably, most parents (27) ______ are always worrying about their children's safety buy mobile phones for them to track their whereabouts. We can also assume that (28) ______ phones to avoid missing out on social contact. In this context, the advantages are clear. (29) ______ teenagers want mobile cannot deny the fact that text messages have been used by bullies to intimidate fellow students. There is also (30) ______ evidence that texting has affected literacy skills.