Manufacturers Were Subdivided into Groups by Volume of Sales

Multiple Choice

Manufacturers were subdivided into groups by volume of sales. Those with more than $100 million in sales were classified as large; those from $50 to $100 million as medium size; and those between $25 and $50 million..., and so on. Samples were then selected from each of these groups. What is this type of sampling called?

A) Simple random
B) Stratified random
C) Cluster
D) Systematic