among following dipole-dipole as major interaction is present in

1) benzene and CCl₄

2) benzene and C₂H₅OH

3) CH₃COCH₃ and CH₃CN

4) KCl and water

Dipole-Dipole as a major ​interaction is present in acetone and acteonitrile as both are polar in nature. Whereas in case I, Vander wall forces will operate, In case II, again vander wall forces, In case 4 ion -dipole interaction will operate.
Hence, the correct option is 3.