Which strategy is NOT a function of effective purchasing?

The correct choice highlights that maximizing production downtime is not a function of effective purchasing. Effective purchasing aims to enhance operational efficiency, which includes minimizing production downtime, not maximizing it. The overall goal is to ensure that materials and products are procured in a manner that maintains a smooth production flow, reduces interruptions, and supports the company's operational needs.

In contrast, reducing transaction costs is a key objective of effective purchasing. This involves streamlining processes, negotiating better pricing structures, and eliminating unnecessary expenditures. Increasing supplier diversity also aligns with effective purchasing strategies as it can lead to a more resilient supply chain, greater innovation, and more competitive pricing. Additionally, negotiating favorable terms is an essential aspect of purchasing, as it ensures that the business secures the best conditions for payment, delivery, and quality from suppliers. Therefore, the focus on maximizing production downtime does not align with the strategic approach of effective purchasing.