Why Would a Reputable Researcher Use a Secondary Source Instead

Why would a reputable researcher use a secondary source instead of a primary one?

A) The primary publication is written in a language not currently spoken.
B) The primary source is located in a museum 1100 miles away, and the cost of travel to review it would be prohibitive.
C) The primary publication is so steeped in jargon that it is very difficult to decipher.
D) The researcher has limited time and cannot squander it searching for primary sources.
E) The primary publication describes only the beginnings of a theory, and a later publication presents it in its entirety.
F) There have never been any primary sources in this area.
G) The primary publication is no longer in print, and there are no existent copies.