A Survey of Online Consumers Asked Respondents to Indicate How

A survey of online consumers asked respondents to indicate how much money they spent for online purchases during the most recent Christmas holiday season.These data were analyzed to see if gender and income level influence the amount consumers spend online for holiday shopping.Which of the following statements is true?
I.This is an experimental study.
II.This is a randomized block design.
III.This is an observational study.

A) I only
B) II only
C) III only
D) Both I and III
E) Both II and III