Have everything in control and in order and discuss about different issues.
Just show a picture so I can help ur information is misleading...
I think the answer would be C
Answer:
24.71 mm
Explanation:
Distance is proportional to focal length, so
d∝f
which means

Magnification of first lens

and

Similarly, magnification of second lens

and

From the above equations we get

and

which means,

and

So, we get

∴ Focal length should this camera's lens is 24.71 mm