A paradox is a literary device in which two statements or ideas appear to contradict each other but may, upon closer examination, reveal a deeper or unexpected truth. The key word in the question is "apparently contradictory" - the contradiction is on the surface, not necessarily real.
Classic examples of paradox include statements such as "I must be cruel to be kind" (cruelty and kindness seem contradictory, yet the statement makes sense when understood as tough love) or "The child is father of the man" (a child cannot literally father an adult, but the statement conveys that childhood experiences shape the adult one becomes).
The other devices are distinct. Irony involves a discrepancy between what is expected and what actually occurs, or between what is said and what is meant. It does not require two statements that seem to contradict each other. Parallelism is a structural technique in which similar grammatical forms are used for balance and rhythm ("I came, I saw, I conquered"). It is about similarity of structure, not contradiction. Contrast simply places two different things side by side to highlight their differences, but contrast does not require the apparent impossibility or logical tension that defines paradox.
When a question specifies "apparently contradictory," it is pointing directly to paradox. The word "apparently" is the signal: the contradiction looks real but hides a coherent meaning beneath the surface.