In a right triangle sum of square of two sides is equal to square of third sides (i) 202+222=884 and 242=576 ∴202+222≠242 (ii) 152+322=1249 and 372=1369 ∴152+322≠372 (iii) 112+602=3721 and 612=3721 ∴112+602=612 (iv) 192+402=1961 and 412=1681 ∴192+402≠412 Hence, option (C) is right triangle.