I am thinking that maybe the problem is not with the calibration. It might be that the buffered solution is already expired since at this point the solution is already not stable and will give a different pH reading than what is expected.
In the diagram, the ship send sound(?) waves to the water, to determine if there is anything there. If there is something like a sunken ship shown in the diagram, the waves return in a shorter time hence you can understand if theres something or now. This is the principle of radars and sonars.
the answer is b. it's commercially reprocessed
Distance= speed (multiplied by) time