Hi @clent - this question is tricky!
There are two considerations covered in the answer choices - whether the space must, or cannot, exceed 10% of the floor area allowed, and whether or not the space must be separated from the main area.
Since the 4 storage rooms, taken together, equal 9.9% of the main space, they don’t require fire separation from it and are considered accessory spaces. Therefore, B is the only choice where both statements are true.
C is incorrect even though the first part of the statement is true - the spaces do not require separation in the given scenario because they’re less than 10% of the main space.