Partner opens one diamond in 1st seat, right hand opponent passes, and it’s your turn. You hold a nice nine points with those three kings, including that K 10 9 fourth holding in the heart suit. Also, you have help in partner’s diamond suit. Should you respond one heart or one notrump?
I recommend a response of one heart, staying disciplined about responding “four card majors up the line”. It’s true that you have a balanced hand, but partner may not. You don’t want to miss the golden 4-4 fit in hearts if there is one. If partner turns out to have a balanced hand, you can always land in a notrump contract.