Final answer:
The best tool to determine the use of a selected SMAW electrode is the manufacturer's guidelines, as these provide detailed, product-specific instructions, ensuring proper usage and safety.
Step-by-step explanation:
To determine the most appropriate way to use the SMAW electrode you have selected, the best tool is c) Manufacturer's guidelines. These guidelines provide specific information on the use of their products, including the correct amperage settings, polarity, and types of materials that can be welded with that electrode.
Opting for trial and error or relying solely on personal preference can result in weld defects or safety hazards, while consultation with colleagues can be helpful, but it may not provide all the necessary details that are specific to the electrode in question.