The electric field of an electromagnetic wave in free space is given by →E=10cos(10⁷t+kx)ˆjV/m, where t and x are in seconds and metres respectively. It canbe inferred that
(a) The wavelength λ is 188.4 m
(b) The wave number k is 0.33 rad/m
(c) The wave amplitude is 10 V/m
(d) The wave is propagating along +x direction

Which one of the following pairs of statements is correct?

a. a and b
b. b and c
c. c and d
d. a and c