In flow through a convergent nozzle, the ratio of back pressure to the inlet pressure is given by the relation
If the back pressure i slower than PB given the above equation,then
(a) The flow in the nozzle is supersonic
(b) a shock wave exists inside the nozzle
(c) The gases expand outside the nozzle and a shock wave appears outside the nozzle
(d) a shock wave appears at the nozzle exit