The correct option is HARD PLEASURE.
An oxymoron refers to a compound word (two words written together) whose meaning are contradictory to each other. The two words that are used together in oxymoron usually have completely opposite meaning and authors usually use it to engage the interest of the readers. For instance in the correct option mentioned above, hard and pleasure has opposite meanings. Other examples of oxymoron are: same difference, bitter sweet, alone together, open secret, original copy, etc.
By asking only the limits of something like There is limited Coca Cola
Selfish people care only about themselves Theyre dangerous because they wouldnnt help a Hurt Person