D. 1 × 10⁻⁴ m
Electromagnetic waves travel through space with the speed of light which is approximately 3.0 ×10⁻⁸ m/s.
The speed is calculated as follows:
Where λ is the wavelength of the wave, f the frequency and c the speed of light.
=(3×10⁸ m/s) / (3×10¹²Hz)
Wavelength, λ= 1 × 10⁻⁴ m
nacl is added to the aqueous of what? ? in order to get a proper answer you have to specify the exact composition of the aqueous solution.
i would say b
but i think i would need more information than that