Final answer:
The operating effectiveness of controls in internal control is tested by tests of controls, which assess whether procedures are effectively preventing or correcting material misstatements.
Step-by-step explanation:
In the context of internal control evaluation, the operating effectiveness of controls is primarily tested by tests of controls. These tests specifically assess whether the control procedures are functioning as intended and are effective in preventing or detecting and correcting material misstatements in the financial statements.
Flowcharts verification may assist in understanding the process and decision tables might help in documenting the logic of system-related controls, but they do not directly test the operating effectiveness.
Substantive procedures, on the other hand, are designed to detect material misstatements at the assertion level and do not directly test the effectiveness of controls.
The correct answer to the question is B. Tests of controls.