What are some of the conditions that you should check for control effectiveness?

Answer: A — Accelerator, brake controls, clutch, horn

Control effectiveness refers to the function and safety of the major controls within a vehicle. This includes the accelerator, brake controls, clutch, and horn, all of which are necessary for proper operation and should be regularly checked for safety. The other options (B, C, D) are either irrelevant or do not directly correspond to the controls in question and should not be considered in this context.