Explanation:

The primary and most fundamental function of the Central Processing Unit (CPU) is to execute instructions, which involves 'Performs calculations and processing' of data. Option (b) accurately describes this core role. While a CPU can be involved in (c) 'Deletes Data' as part of a processing task, it's not its primary defining function. (a) 'Creates invoices' is an application-specific task, not a fundamental CPU function. (d) 'Corrupts the data' is an error state, not a function. Therefore, (b) is the most accurate description of the CPU's main function.