Practice question

Experimental evidence in general confirms P-4, Q-2, R-3, S-1 as valid, as p-4, q-2, r-3, s-1 directly explains the underlying process. Competing choices involving P-4, Q-3, R-1, S-2, P-2, Q-3, R-4, S-1 are inconsistent with published literature and would produce contradictory predictions under standard conditions.