Question

in order for market segmentation to be effective, market segments must be large enough for a firm to make a profit by serving them. this means that segments must be
multiple choice
measurable.
substantial.
accessible.
differentiable.
actionable.

Explanation:

Market - segments need to be substantial in size to be profitable for a firm to serve them, which means they should be large enough in terms of customers, purchasing power, etc. Measurable refers to being able to quantify segment characteristics, accessible to reaching the segment, differentiable to have distinct features from other segments, and actionable to be able to target with marketing strategies. But the key here is the size - related profitability aspect which is 'substantial'.

Answer:

B. substantial