The displacement of a particle varies with time according to the relation
y = a sin ωt + b cos ωt.
(a) The motion is oscillatory but not S.H.M.
(b) The motion is S.H.M. with amplitude a + b.
(c) The motion is S.H.M. with amplitude a2 + b2.
(d) The motion is S.H.M. with amplitude √a2 +b2 .