Final answer:
The method for handling non-standard adjustments in a car audio system, as requested by Mr. Flex, is best handled by Customizing. This involves altering the product to meet specific client needs, unlike standardizing, rejecting, or ignoring.
Step-by-step explanation:
When adjustments to a product or service are requested, such as non-standard items being incorporated into a car audio system, the method for handling these adjustments is by Customizing. Customizing refers to making modifications or alterations to meet a particular client's needs or preferences, ensuring that the end result is tailored to what the client has requested. In the context of Mr. Flex's scenario, standardized solutions would not meet the specific requirements set forth by his client for the audio system. Therefore, rejecting or ignoring the client's requests are not productive solutions, and the act of customization aligns with providing high-quality client service in a professional setting.