So the question is:
A digital camera has a lens with a focal length of 10 mm. The image sensor, i.e. the photosensitive part of the camera has 7.5 x 7.5 μm pixels. A test map with a variety of closely spaced line pairs (see figure) is located at 1.0 m from the lens. How narrow can the black bars (on the test map) be in order to be resolved by the digital camera? Note that in this case the resolution is only limited by the size of the pixels.
Now, my guess is that you solve this question with the help of the depth of field formula. $$ s \approx \frac {a^2} {1000f}b_t $$ Where 'a' is distance to the object, 'f' is the focal length of the lens and 'bt' is the aperture number. As we know 'a' is 1 meter, 'f' is 0.001 meter. And since the last sentence says "... the resolution is only limited by the size of the pixels" it gives that. $$ s \approx b_t $$ Now, from there I don't really know where to go. How do I use the 7.5 x 7.5 μm pixels? Pretty lost.
