The speed of a sound wave depends on
a. the air temperature.
b. its frequency.
c. its wavelength.
d. all of the above
e. none of the above

-- Frequency and wavelength are reciprocals of each other.
Frequency = 1/wavelength and wavelength= 1/frequency.
So anything that's related to either frequency or wavelength
is related to the other one.
If the speed of sound depends on one of them it depends
on both of them.

If the speed of sound depended on frequency (wavelength),
then there would be no such thing as bands, orchestras,
singers, or guitar chords.  In an orchestra, the flutes make
sounds with high frequencies, the tubas and big drums make
sounds with low frequencies, and all the other instruments make
sounds with frequencies in between.  They might all play together,
but if their sounds traveled through the air at different speeds, then
by the time their sounds reached you at the other end of the arena,
they would be all spread out, and you'd hear them all at different times.
It would be a total mess.

The speed of sound doesn't depend on the frequency (wavelength)
of the sound.

That leaves only one other choice on the list.

The speed of sound DOES depend on the temperature of the air
it's traveling through.