A concept or characteristic that is used to subdivide the population into smaller groups is known as:

Correct option is B

The correct answer is (b).
Introduction
A stratum is a distinct subgroup within a population, defined by a specific characteristic (e.g., age, gender). Stratification helps ensure representation in sampling.
Information Booster

• Stratum: subset sharing a particular attribute.
• Used in stratified random sampling to increase precision.
• Sample is a subset taken from the population.
• Population is the entire group.

• Sample is not a subdivision.
• Population is the whole.
• Focus is not a statistical term.