Which entity has the principal responsibility to control the execution of processes?

A. Operating system

B. Process control block

C. Memory

D. Dispatcher

Answer: B) Process control block

Explanation: Process control block (PCB) is the block that is in the form of the data structure containing data and its processing actions. The tasks that come under the PCB are controlling the data in block, entering the data in table, processing the data etc.

The other given options are incorrect because operating system is the system on which the whole processing of task are done, memory stroes the data and dispatcher is the data dispatching unit. So, the correct option is option (B).