Which of the following is an example of an interaction with mass media? A. Estelle has a face-to-face conversation with her teacher.
B. Anna reads an article in the newspaper.
C. Chang's mother leaves a note for him on the refrigerator door.
D. Issac calls his friend on the phone.

this is b. how railways dealt with people riding the trains without paying

the following key ideas correctly express the key sentence.

restate key idea: most people can learn to swim in ten short lessons.

restate key idea: the majority of water-accident victims require mouth-to-mouth breathing.

restate key idea: an empty, tightly closed gallon jug will support a tired swimmer.  

restate key idea: first aid is to prevent accidents as well as assist in rescue.

explanation: the key idea needs to have the same topic as the key sentence (drowning and safety).