Which of the following is a major benefit of using modular design?

Modular design focuses on creating products with interchangeable components or modules. This approach significantly enhances the ability to easily repair and upgrade products. When a product is designed modularly, individual parts or sections can be replaced or upgraded without needing to replace the entire unit. This not only simplifies maintenance but also allows for customization and the incorporation of new technology over time, making products more adaptable to changing needs.

This benefit contrasts sharply with the other options. Higher initial costs can be a downside of modular design due to the complexities involved in developing interchangeable components, while more complex product structures can arise from the introduction of multiple modules. Additionally, modular design aims to improve the availability of parts by standardizing components across different products, rather than reducing their availability. Hence, the simplification of repairs and upgrades stands out as the core advantage of using modular design.