A serial continuous process having four stages is running for $24$ hours daily. Between any two stages, there is a buffer. It takes the first stage $3$ hours to process a unit, the second stage $6$ hours, the third stage $4$ hours, and the fourth stage $6$ hours.

Which statement is correct?

Group of answer choices

Two bottlenecks exist in this process; and the capacity of process is $4$ units$/$day$.$

Only $1$ bottleneck exists in this process; and the capacity of process is $8$ units$/$day$.$

Only $1$ bottleneck exists in this process; and the capacity of process is $4$ units$/$day$.$

Two bottlenecks exist in this process; and the capacity of process is $6$ units$/$day$.$

Only $1$ bottleneck exists in this process; and the capacity of process is $6$ units$/$day$.$