Http://i63.tinypic.com/2gxmomo.jpg - Question 19 - why is the answer (d)..?

19.
A. True
As the "average" oxidation state of S increases from +2 (in K₂S₂O₃) to +2.5 (in K₂S₄O₆), S is oxidized.

B. True
As S is oxidized, K₂S₂O₃ is the reducing agent in the reaction.

C. True
The solution of I₂ is reddish-brown, while all of the solutions of K₂S₂O₃, K₂S₄O₆ and KI are colourless.

D. False
The oxidation state of iodine decreases from 0 (in I₂) to -1 (in KI).