These questions below consist of a set of labelled sentences. Out of the four options given, select the most logical order of the sentences to form a coherent paragraph.

We have seen that, when

X.  think of it as losing its parts and shrivelling to a point
Y.  occupy any portion of space, we need not
Z. we deny that a mental image can

• ZXY

• YZX

• YXZ

• ZYX