Fermentation Reactors - Medical Science

Q1:

In batch culture, protogon is produced from peptone during the stationary phase with a yield of 0.4 protogon mg per g of peptone. If it is to be produced in a chemostat at a dilution rate of 0.5 h-1 from a medium containing 10 g.l-1 of peptone, then the rate of protogon synthesis would be

A 0 g.l-1h-1

B 0.5 g.l-1h-1

C 1 g.l-1h-1

D 2 g.l-1h-1

ANS:A - 0 g.l-1h-1

How is it due to stationary phase? @Mark.