Instead of matching one by one, first eliminate the easy pairs. An elbow meter's whole identity in textbooks is its uncertain, bend dependent discharge coefficient, and the number quoted, 0.63 to 0.83, is the standard figure for it, so elbow meter locks onto flow coefficient 0.63 to 0.83 immediately.
Next, a Pitot tube is a point velocity device, and its defining feature in setup is the manometer used to sense the tiny stagnation-static pressure difference, an inverted U-tube manometer is the standard choice when this difference is small, so Pitot tube pairs with inverted U-tube.
An orifice used for open discharge from a pipe is mounted right where the pipe ends, the jet shooting out is what you measure, so orifice pairs with end of pipe.
That leaves the Venturimeter, which by elimination and by its actual purpose, measuring flow rate in a closed pipeline, pairs with discharge measurement.
Combining all four gives (A)-(IV), (B)-(II), (C)-(I), (D)-(III).
\[\boxed{\text{(A) - (IV), (B) - (II), (C) - (I), (D) - (III)}}\]