Playing Detective 

1) West. There are 27high-card points between the North-South hands, leaving only 13 for East-West. West must have the A to have enough points to open 1. 2) East or West. Although West is a favorite to hold all the outstanding high cards, it's just possible East could have the J. West's oepning bid could include some distributional values as well as high cards. 3) Lead a club and finesse the C10. The DA is the only entry to dummy. Use it to take a finesse against the CJ, hoping the complete deal looks like this:

NORTH (Dummy) 8 7 5 J 9 6 3 A 8 4 7 6 2   WEST 6 2  Q 8 5 K Q J 7 5  A 9 3 EAST 10 4 3 10 7 4 2 10 3 J 8 5 4   SOUTH (You) A K Q J 9 A K 9 6 2 K Q 10

You have to lose two diamond tricks and the A, so you can't afford to lose a trick to the J. You could hope West holds the doubleton AJ so that the J will fall under the KQ. But that's less likely than the chance East has the J.