Toddlers (18 to 36 months)
Can be easily angered because:

(a) they think they are the center of the world and can be frustrated when they cannot do or have what they want.
(b) it is difficult to share things.
(c) they have a strong notion of what belongs to them.
(d) they still don't know many words, can't speak well, and can be upset and angry because people don't understand them.
(e) have difficulty controlling their feelings.

They show anger with tantrums.