Player C in the above example cannot intercept because to intercept you need to be between the thrower and the target square, which he is not.The Rules wrote: Interceptions
One player on the opposing team may attempt to intercept a
thrown ball. To be able to make an interception, the player must:
• have the plastic ruler pass over at least part of the square the
intercepting play is standing in, and …
• have a tackle zone, and …
• be closer to the thrower than the thrower is to the target
player/square of the pass, and …
• be closer to the target player/square of the pass than the
thrower is to the target player/square of the pass.
Taking the above example you could intercept from the Bold X squares which are all eligible using the rules as stated above.
XAX
XXX
XXX
XXX
CBX