Quantity A: The number of integers in the set that are less than or equal to 20

Quantity B: The number of integers in the set that are greater than or equal to 20

This question was on the Manhattan platform. I think the answer should be C as I thought that the set will have distinct integers. But according to the Manhattan Prep, we can also have repeated terms which makes the correct answer to be D. What definition does ETS use for sets?

I could be wrong, but I think that if ETS wants us to think of a set, where all integers are different, they add an extra word to specify that
For eg. A set of unique integers
Otherwise we are to assume that there can be repeats

This may sound confusing but basically if you see set of integers or data set on the GRE, treat it as a list. This means that repetitions are allowed and counted as separate elements. If the question was referring to elements that are all different, it would have said that the integers are distinct or unique.