Station $2$ Machine A $15$ min$/$unit

Station $4$ Machine A $60$ min$/$unit

Station $16$ min$/$unit

Station $2$ Machine B $15$ min$/$unit

Station $310$ min$/$unit

Station $4$ Machine B $60$ min$/$unit

Station $4$ Machine C $60$ min$/$unit

A manufacturing plant has four stations in the assembly line $($illustrated in the image above$).$ A unit needs to be processed at either Machine A or Machine B for Station $2($parallel lines, both lines performing the same operations$).$ The box is then processed at Station $3.$ After that, the unit needs to be processed at either Machine A$,$ Machine B or Machine C in Station $4$ before leaving the production line. The process time of each station$/$machine is indicated in the flowchart. What is the capacity rate of this system measured in units$/$minutes$?$

$3$ units$/$minute

$0\mathrm{.}08$ units$/$minute

$20$ units$/$minute

$0\mathrm{.}05$ units$/$minute