Final answer:
The category of resources that IHR managers and others must develop and maintain is human capital.
Step-by-step explanation:
The category of resources that IHR managers and others must develop and maintain is human capital. Human capital refers to the knowledge, skills, abilities, and experience of individuals that can be used to contribute to the organization's goals.
IHR managers need to invest in hiring the right people and then continue to train and develop them to maximize their potential and benefit the organization.
Investing in technology is also important to improve efficiency and effectiveness in managing resources. It can streamline processes, automate tasks, and provide tools for better decision-making.
Lastly, physical plant and equipment are also essential resources that need to be developed and maintained. These include facilities, machinery, and tools that enable the organization to carry out its operations.