Opener's Rebid after Partner's Negative Double 4

Opener's Rebid after Partner's Negative Double 4

Question:

You are South. Matchpoints. None vul. 

You hold: 

KJ3
KJ6
KQ108
AJ2

What is your next call on this auction:

  West    North    East    South  
   1diamonds icon
1hearts iconDbl Pass?

Answer: