An Advocacy Group Is Interested in Determining If Gender (1

An advocacy group is interested in determining if gender (1 = Female, 2 = Male) affects executive level salaries.They take a random sample of executives in three different Industries: (1 = Consumer Goods, 2 = Financial, 3 = Health Care) .Salary data are collected.
Which of the following statements is true?
I.This is an experimental study.
II.This is an observational study.
III.This is a randomized block design.

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