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.
In the chain _W W Z, which of the following would be substituted for the dash to make a chain?
I. Z
II. W
III. T

Options

A. I only
B. II only
C. I and II only
D. I, II and III

Answer

C

Explanation

Substitute each letter for the dash and test each result.
I. Z W W Z. This is consistent with all of the initial conditions, so this is a possible chain.
II. W W W Z. This is consistent with all of the initial conditions, so this is a possible chain.
III. T W W Z. This violates the condition that T may not be on the end of a chain, so this is not a possible chain.