$1$d$.$ What is the flow rate if the demand rate is $15$ units$/$hour$?$ Assume there is no limit on the available input.

Flow rate $=$ minimum$\{$available input, demand rate, process capacity$\}$

Select one:

a$.2$ units$/$hour

b$.6$ units$/$hour

c$.12$ units$/$hour

d$.15$ units$/$hour