The steps in B are due to the fact that the particles produced in a lytic cycle must reinfect other cells to produce more particles. The flat "step" represents the time for reinfection and production of more particles.
Work Step by Step
The thing to do is to review the lytic cycle and to see that the host cell dies. It cannot make more particles once it has lysed so there is a lag period while reinfection of more host cells occurs.