Marconis conception

[crackgmat007]

Marconi’s conception of the radio was as a substitute for the telephone, a tool for private conversation; instead, it is precisely the opposite, a tool for communicating with a large, public audience.
A. Marconi’s conception of the radio was as a substitute for the telephone, a tool for private conversation; instead, it is
B. Marconi conceived of the radio as a substitute for the telephone, a tool for private conversation, but which is
C. Marconi conceived of the radio as a tool for private conversation that could substitute for the telephone; instead, it has become
D. Marconi conceived of the radio to be a tool for private conversation, a substitute for the telephone, which has become
E. Marconi conceived of the radio to be a substitute for the telephone, a tool for private conversation, other than what it is,

OA - C

[Arsene Lupin]

I guess the issue with all the other choices is the first comma. The phrase that comes next is modifying the wrong word. It should modify the radio not the telephone.