Consider the following statements regarding the polarisation of waves:
(a) Polarisation is observable only in waves whose particle displacement is perpendicular to the direction of propagation.
(b) Sound waves in air can be polarised using suitable mechanical filters.
(c) Electromagnetic waves are transverse and hence exhibit polarisation.
(d) Longitudinal mechanical waves cannot be polarised because their oscillations are parallel to the direction of propagation.
Which combination of statements is correct?
a) (a) and (d) only
b) (c) and (d)
c) (a),(c) and (d)
d) (a) and (c)