(a) Custard, the dragon
(b) To tease/ make fun of him
(c) Ink- black kitten, Blink- the little grey mouse, Mustard- a little yellow dog / they are Belinda’s pets
(d) because he was a coward
Detailed Answer :
(a) The dragon was tickled by Belinda.
(b) She tickled 'him' because it was very scared and cried for a safe cage. They all laughed at it as it was a coward.
(c) Ink the letter black kitten, Blink, the little grey mouse and Mustard the little yellow dog are the brace pets of Belinda who herself was a brave girl.
(d) They all laughed at him because the dragon though fierce looking was ridiculed timid and coward so they all ridiculed him.