What are the advantages and disadvantages of doing (a) telephone interviews

Q:  Suppose your dean of admissions is considering surveying high school seniors about their perceptions of your school to design better informational brochures for them. What are the advantages and disadvantages of doing (a) telephone interviews and (b) an Internet survey of seniors requesting information about the school?

Q: (a) Why might a marketing researcher prefer to use secondary data rather than primary data in a study? (b) Why might the reverse be true?

Q:What variables might be used to segment these consumer markets? (a) lawn mowers, (b) frozen dinners, (c) dry breakfast cereals, and (d) soft drinks.