Respuesta :
Answer: communications devices available over the last century.
Alina wants to research communication devices from the telephone to modern times. This is mostly contained within the last century, so it would be a good place for her to begin her research. If she were to research only modern times, she would not gain information on all the devices she is interested in. Researching the inventors of the devices would lead her to a different area than the one she wants to learn about. Finally, focusing on video-conferencing would greatly limit her scope and force her to leave out most of the information she needs.