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,


OG says option A is wordy and awkward.Please explain what is awkward in A and also is there any other error in A?