Why are the following lines ironic?

"'my name is ozymandias, king of kings:
look on my works, ye mighty, and despair! '"

a. ozymandias never ruled anything.
b. the inscription was intended to "mock" the king that the statue portrays.
c. we know that shortly after the statue was erected, ozymandias was killed in a battle with the persian empire.
d. all of the great works of the king have decayed to ruin.
e. none of these

d. All of the great works of the king have decayed to ruin.

Explanation:

The given lines “my name is Ozymandias, king of kings, look on my works, Ye mighty and despair” are ironic because even his statue which is so large has been destructed. It hints on the fact that pride and materialistic power is a temporary thing and it will eventually end. Everything in world is subjected to decadence. This is what happens with Ozymandias and the speeches given by him is a decay.

one context clue that me find the meaning of luxuriance was that the base word of luxuriance is luxury, so i think that luxuriance means something that is luxury, or something luxurious.