Even though each item on the distance ladder is only effective within a certain distance range, the concept is still effective because

A) distances are ultimately relative, and not absolute.

B)each technique produces exact distances on its own.

C)each step can be calibrated through its overlap with the previous step.

D)the distance ladder concept can be verified by looking in different wavelength ranges,

E)the time delay due to light travel time is significant enough to limit the accuracy of distance measurements anyway.