An Attempt to Start a Process on Resource BP0100 Has

An attempt to start a Process on resource BP0100 has resulted in the following error message: BP0100 is too busy to run that process Which of the below is the most likely cause of this error?

A) Resource BP0100 is offline
B) There is more than one instance of the Blue Prism resourcepc command running on resource BP0100
C) The BPServer service is not running on the Blue Prism Application Server
D) A Process is running on resource BP0100 that calls a Business Object with a run mode of 'Exclusive'