If p and q are the efficiencies of a Brayton & Rankine cycles respectively in a Brayton-Rankine combined plant, the efficiency n of a combined plant is?

• A. n = p/q
• B. n = p+q-pq
• C. n = pq
• D. n = (1 ‚Äö√Ñ√∂‚àö√ë‚àö¬® pq)