Choose the word or phrase (A; B; C or D) that best completes the sentence

E-mail, and chat rooms let children communicate (33) ________ friends and family members. They can also allow children to connect with people that they have never met in person. Knowing a little about each of these communication services can help parents keep children safer while online. Through e-mail, (34) ________ can easily send and receive messages. These messages may also have text, audio, and picture files attached. Signing up for an e-mail account is simple (35) ________ most services offer them for free. Sometimes these messages contain viruses, or other inappropriate content, so parents should warn children to be wary of e-mails from (36) ________ people. Chat rooms are online hang-out spots where anyone can talk about anything - current events, books, and other common interests. Users often do not know each other in real life, so it is important that parents keep a close eye on the content of any (37) ________
33. A. to    B. with                 C. for                  D. through
34. A. receivers    B. messengers       C. users              D. partners
35. A. due to    B. because            C. because of       D. so
36. A. known    B. well-known       C. unknown          D. unpopular
37. A. conversations    B. meetings            C. letters             D. users