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