Read the passage:

one day, soon after this, the little bird fluttered up against the windowpane and beat his wings against it in vain effort to get out. a new idea seized the young prince. he took up a golden jar, went to the window, and struck on one of the checkered panes of glass with all his force.

"you shall be free, even if i cannot be," he said to the bird. two or three strong blows shivered the small pane, and the bird swept out into the free air beyond.

"ah, my pretty one, how glad i am that you are free at last! " cried the prince, watching the flight of his fellow prisoner. his face was bright with glad, unselfish joy.

which theme does this passage develop?

a. be kind to animals

b. others often brings greater joy than ourselves.

c. selfishness

d. greed