$($a$)\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_$ is an approach to creating a network diagram and schedule where the sequence and dependent relationship of activities account for limited quantity and availability of resources while $($b$)\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_$ is an approach to creating a network diagram and schedule which demonstrates a serial relationship among activities on a network diagram where tasks must be performed in a specific technical order.