Average length of a surgery session is 165 minutes. With a decrease in the number of doctors, this will have to increase. Hence, we eliminate options A, B and C. This leaves us with D and E.
165 x 5000 = 4500 x new length of surgery required
New length of surgery = (165 x 5000) / 4500 = 183.3333…
Hence, 183 is the answer (D)