(a) If partner leads S3 you should play the 9
(b) If partner leads H3 you should play the King
(c) If partner leads D3 you should play the Ace
(d) If partner leads C2 you should play the 10
There are guidance rules to remember when partner has led from length and declarer plays low from dummy-
IF YOU HOLD THE Q OR THE K, AND DUMMY HAS Jxx(x) OR Qxx(x), you should
(a) play your next highest card if it is the 9 or 10.
(b) play high if your next highest card isn’t the 9 or 10
IF YOU HOLD THE ACE AND DUMMY HAS Jxx(x), YOU SHOULD PLAY THE ACE
IF YOU HOLD THE ACE AND DUMMY HAS Qxx(x) OR Kxx(x), you should
(a) play your next highest card if it is the 10 or Jack.
(b) play your Ace if your next highest card isn’t the 10 or Jack
There are situations where exceptions arise, but if you follow these basic guidelines you’ll gain lots of defensive tricks in the long term.