PREP-1-44

44.   Scientists at the Los Alamos National Laboratory have succeeded for the first time in mining heat from the Earth's interior and producing energy on a commercial scale, enough for efficient generation of electricity and heating factories and homes.
(A) and producing energy on a commercial scale, enough for efficient generation of electricity and heating
(B) and producing enough energy on a commercial scale for electricity to be generated efficiently and to heat
(C) for energy production on a commercial scale, enough for generating electricity efficiently and to heat
(D) to produce energy on a commercial scale, enough for generating electricity efficiently and for
(E) to produce enough energy on a commercial scale for efficient generation of electricity and heat

prep解释说heat和produce平行，为什么不能看作 efficient generation of (electricity and heat)