D for me.
+1 for great question.
This is a mess of misplaced modifiers and diction. What is heating the homes ? what is producing the heat ? I had to read it a few times to "get" the meaning. But once I understood the meaning, the question was easy to solve.
I interpret it as Scientists mined heat to produce energy --> which will heat factories and homes (and be efficient enough to do so).
Based on this interpretation, I can't look beyond D.
sondenso wrote:
36. 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 heating
E. to produce enough energy on a commercial scale for efficient generation of electricity and heat