You answered that you would bid 1 Heart. This is correct  because with a Black singleton, you bid the suit in the middle.

If, as you might expect to happen, your partner replies with 2 Clubs, you can then bid 2 Diamonds. If however, he bids Spades or Diamonds, you can support him, and if he supports your Hearts, you can stop there. You might wonder, when he bid the Spades why No Trump wouldn't have been a good option. The answer to that is that if you rebid in No Trump, it promises a certain number of points. If you say 1 No Trump as a rebid, that promises 15-16 points, while 2 No Trump would mean 17-18 points and 3 No Trump would mean 19+ points. However, if because the way the bidding went, you had to go to 2 No Trump as your rebid, that would promise 15-17 points, and 3 No Trump would mean 18-19.

All the rebids are put in a table which you might find useful.

Going back to our example hand. Let us say that you opened 1 Heart, and the player on your left No Bid. Your partner has this hand.

Spades              J,7,3,2
Hearts              10,8
Diamonds         A,J
Clubs                K,Q,10,8,4

Response bidder certainly has sufficient points to make a bid. He doesn't like your Hearts, and his Spades are really too weak to consider going into No Trump at this stage. So he bids 2 Clubs.

Assuming that the other opposition player also No Bids, you now have to make a rebid with your hand.

Spades             A,Q,8,4
Hearts              K,9,7,3
Diamonds         K,Q,8,3
Clubs                7

You now know that your partner has at least 10 points, or he wouldn't have taken the bidding to the 2 level. You have insufficient points to rebid 2 No Trump, so you bid another of your 4 cards suits, and bid 2 Diamonds.

Your partner likes Diamonds, but suspects that there is more to the hand than just a 2 Diamond bid, but to bid 3 Diamonds would be misleading, as he has only 2. He could repeat his Clubs, but that would make it seem like Clubs was the only suit he was prepared to play in. If he bids 2 Spades at this stage, he tells his partner he has 5 Clubs and 4 Spades, (Because if he had 5 of each he would have bid the Spades before the Clubs) and that there probably is a game somewhere, but he isn't quite sure where.

So the bidding sequence so far is: 1 Heart, NB, 2 Clubs, NB, 2 Diamonds, NB, 2 Spades, NB

33. What would your next rebid be?

a. No Bid
b. 3 No Trump
c. 4 Spades