Consider a process that has $3$ stations, ordered in sequence: A$,$ B and C$.$ At each station, two consecutive tasks are performed one after the other. The time $($in seconds per unit$)$ it takes for a single person to perform each task is given in the table below $($e$.$g$.,$ task A$2$ takes $10$ seconds per unit$)$:

Station

# of

Workers

Task

A$1$

Task

A$2$

Task

B$1$

Task

B$2$

Task

C$1$

Task

C$2$

A

$1$

$20$

$10$

$-$

$-$

$-$

$-$

B

$2$

$-$

$-$

$40$

$40$

$-$

$-$

C

$1$

$-$

$-$

$-$

$-$

$15$

$5$

The table also gives the number of workers at each station. There is ample buffer capacity between each station. What is the capacity of this process $($in units per minute$)?$

Question $2$ options:

$2$

$2\mathrm{.}5$

$3$

$1\mathrm{.}5$