A white light is, by definition, apparently colorless light, for example ordinary daylight. It contains all the wavelengths of the visible spectrum at equal intensity.
so A.
The third one sliding friction
Explanation:
Answer:
C is halved
Explanation:
The frequency and the wavelength of a wave are related by the equation:

where
v is the speed of the wave
f is the frequency
is the wavelength
From the equation above, we see that for a given wave, if the wave is travelling in the same medium (and so, its speed is not changing), then the frequency and the wavelength are inversely proportional to each other.
Therefore, if the frequency doubles, the wavelength will halve in order to keep the speed constant:

The weight of air resting on a surface, divided by the area
of the surface ... described in units of force per unit area ...
is called air pressure.