in round robin when three processes have to enter the ready queue at the instant , if one process has just finished I/O the other has preempted from CPU due to expiration of its quantum and third (C)...

in round robin when three processes have to enter the ready queue at the instant , if one process has just finished I/O the other has preempted from CPU due to expiration of its quantum and third (C) has just started. which one will be inserted last (ie lowest priority ) ?

a) the process that has just finished I/O

b) One of the three will be random be selected

c) The process that has been pre-empted from CPU  due to expiration of its quantum time.

d) The process that has just started