A researcher studying organic compounds has found that five different molecules - T, W, X, Y and Z-form chains According to the following rules :
i) A chain consists of three or more molecules, though the molecules in the chain are not necessarily different.
ii) T is never found on either end of a chain.
iii) If W appears in a chain, it appears more than once.
iv) X is never found next to Y in a chain.
v) W is never found on the end of a chain unless Z is found somewhere in the chain.
vi) If Y appears in a chain, Z appears also.
Which of the following is not a chain but could be converted into a chain by changing the order of the molecules ?

Options

A. X Y T X
B. W X X W
C. T X X Y
D. W T T W

Answer

D

Explanation

You first have to determine what is wrong with the sequence and then whether or not you can correct it by reordering the letters.
1) There are two difficulties here. One, X is next to Y, two, Y appears with Z. Reordering alone will not provide a Z, so this cannot be changed into a chain just by reordering.
2) Here there are three difficulties: 1) W appears without another W, 2) W is on the end without a Z in the sequence, 3) Y appears without Z. In short, you cannot supply the missing letters just by reordering.
3) There are three problems with this sequence: 1) you have T on the end, 2) X and Y are together, and 3) Y appears without Z. The third cannot be corrected just by reordering.
4) The problem here is that you have won the end without a Z in the to correct this by reordering the letters, c.8-, putting the W s inside the sequence, you wind up with T s on the ends.
This sequence is not a chain because W appears on the end without a Z order: X W W X. This sequence is a chain.