Step 1: Eppley Spectral Radiometer records PAR, so A - (II). This eliminates options (3) and (4).
Step 2: Kipp Radiometer measures diffused solar radiation, so B - (IV), not (I). This eliminates option (1).
Step 3: Only one match survives: (A)-(II), (B)-(IV), (C)-(I), (D)-(III), so the correct answer is option (2).