A clothing chain has recently launched an online store. Online sales have been sluggish compared to their brick and mortar stores, and management suspects that its regular customers have concerns regarding sizing and fit. To determine if this is the case, they plan to survey a sample of their regular customers. The group of all of their regular customers is known as the ________ of the study. (enter one word only)
a) Sample
b) Population
c) Experiment
d) Analysis