A question from red swastika school prelim mcq.

The following materials are classfied under group X, Y & Z respectively. Which of the following is grouped incorrectly?

X--- Envelope, Balloon
Y--- SilK, Cheese
Z--- Thread, Disposable cup

Answer: Cheese

I can't figure out why though.

Please advise. Thanks.

If I am not wrong, the materials in Group X are made from plants once alive. Envelopes are made from paper which comes from trees. Balloons are made from rubber/latex from rubber trees.

In Group Z, the thread may be cotton thread of nylon(or other man-made material) thread. Assuming that it is a man-made material, it corresponds with the disposable cup as that is also man-made.

In Group Y, silk comes from silkworms which are animals. However, cheese is NOT a material.

So there you go!