As we know that rate of change of magnetic flux produces the e.m.f in coil is given by where A & θ are constant so options (a), (b) are correct. Now if magnetic field is constant then above equation can be rewrite as so option (c) is also correct but magnetic field in option (d) is not varying with time. Also the coil is stationary meaning there is no e.m.f hence this option is wrong.

Therefore, options (a), (b) & (c) are the correct.