Answer:
a) Frequency is inversely proportional to the wavelength, then the graphs with smaller wavelengths than A have larger frequency than A.
The correct options are: B and C.
b) The opposite as above, in this case the correct options are: D and E.
c) The ones with the same wavelength will have the same pitch:
A and F seems to have the same wavelength.
B and C also seems to have the same wavelength.
d) The vertical height of the peaks are related to the louder sounds, then the sounds louder than A are: B and F.
e) The one that has a higher pitch (or smaller wavelength) and the same amplitude than A is C.
(you need to measure the height of the peaks in both graphs, and see that are equal).
f) D has a larger wavelength than A, so it would sound "lower", and both waves have the same amplitude, so the loudness will be the same.