Given, A metallic loop is placed in uniform magnetic field B. Magnetic field B and metallic loop are perpendicular to each other. Then, if metallic loop is moved along B or rotated about its own axis, the net flux associated with it remains constant. Thus, no emf will be induced in these cases. However, when the loop is squeezed to a smaller area or rotated about one of its diameters. Then its flux changes. Thus, emf is induced. So, option (b) and (d) both are correct.