A shopkeeper argues: 'Some of my suppliers are registered with the trade body, and some of those registered with the trade body give a written warranty. So some of my suppliers give a written warranty.' Which of the following describes the form of the shopkeeper's reasoning?

Two overlapping slices of the registered group are described, and nothing says they are the same slice: the shopkeeper's registered suppliers may be drawn entirely from those who give no warranty. Linking two 'some' premises through a middle term in this way proves nothing. The first and second options set out valid forms, and the third is faulty but is not the shape of this argument.