LSAT-0112-1-23

It is clear that humans during the Upper Paleolithic period used lamps for light in caves. Though lamps can be dated to the entire Upper Paleolithic, the distribution of known lamps from the priod is skewed, with the greatest number being associated with the late Upper Paleolithic period, when the Magdalenian culture was dominant.

Each of the following if true contributes to an explanation of the skewed distribution of lamps EXCEPT:

A.  Artifacts from early in teh UP period are harder to identify than those that originated later in the period.

B.  More archaeological sites have been discovred from the Magdalenian culture than from earlier cultures.

C. More efficient lamp-making techniques were developed by the Magdalenian culture than by earlier cultures.

D. Fire pits were much more common in caves early in the UP period than they were later in that peirod

E. More kinds of lamps were produced by the Magdalenian culture than by earlier cultures.

Right answer is A. Why A? Does this support the explanation of the skewed distribution of lamps as well? The only explanation I can think of is that, lamp does not belong to "artifacts". Am I on the right track?