Dr Sandeep Wants to Study the Spending Habits in London

Dr. Sandeep wants to study the spending habits in London residents. To study this, he hands out questionnaires about spending habits to all of the students in his introductory psychology class. Dr. Sandeep's data will be ______ because _.

A) invalid; all of his students were residents of London
B) invalid; there is no control group
C) valid; he included all of his students in his sample
D) invalid; he did not use a representative sample
E) valid; he used random sampling