Some rates of exchange did not allow trading because some goods couldn't be split into smaller parts.

• A. Portable
• B. Acceptable
• C. Divisible
• D. Divisibility

Answer: (D)

Divisibility—the ability to split a good into smaller parts for trade—is what this question targets. In a barter system, if a good can’t be divided, you can’t match its value to smaller quantities of other goods, so many exchange rates can’t be used. The sentence describes the problem as arising from the goods’ lack of divisibility, making divisibility the precise noun form that fits best. The other terms don’t capture this idea: portable is about carrying ease, acceptable is about market acceptance, and divisible is an adjective describing the property rather than naming the property itself.