The authors describe efficiency as

A: the optimal use of resources.

To understand how the authors describe efficiency as 'the optimal use of resources,' we can break down the concept and explain it further.

Efficiency refers to the ability to accomplish a task or goal with minimum wasted effort, time, or resources. It essentially means achieving maximum output with minimum input. In this context, the authors are defining efficiency as the optimal use of resources.

To determine how the authors arrived at this definition, we can look at the concept of resources. Resources can include various elements such as time, money, energy, manpower, and materials. The authors are emphasizing that efficiency involves using these resources in the most effective and productive way.

The word "optimal" in this definition refers to the best or ideal use of resources to achieve the desired outcome. It implies that efficiency aims to maximize the output or result while minimizing the input or resources utilized. This could involve identifying and eliminating waste, streamlining processes, utilizing technology, and making strategic decisions to optimize resource allocation.

By considering efficiency as the optimal use of resources, the authors are highlighting the importance of resource management and utilization in any endeavor. This perspective encourages individuals, organizations, and systems to constantly analyze and improve their practices to achieve better results with fewer resources.