Prussia Industries accepts three new jobs for processing in its four-machine job shop. They have a drill, grinder, mill, and lathe. The processing sequence and machine(time) are as follows. All times are in minutes. Job 1: L(15), D(30), M(60) Job 2: D(20), M(20), G(30) Job 3: M(5), G(15), D(30), L(15) Job 1 is ready at time 0; Job 2 arrives at time 20; and Job 3 arrives at time 30. Prussia Industries uses an FNO dispatching rule. What is happening at the milling machine at time 100? a. Job 2 is being processed. b. The milling machine is idle. c. Job 3 is being processed. d. Job 1 is being processed