Introduction:
Human resources refer to the people who make up an organization's workforce and are responsible for carrying out its tasks and achieving its goals. A person becomes a human resource when they meet certain criteria that make them eligible and suitable for employment within an organization. These criteria include being able to work, being willing to work, and belonging to a particular age group.

Explanation:
Human resources are an essential component of any organization, as they are responsible for performing various tasks and contributing to the overall success of the organization. Let's discuss each criterion in detail:

1. Able to work:
To become a human resource, a person must possess the ability to work. This means having the necessary physical and mental capabilities to perform the job requirements. Different jobs may have different physical and mental demands, and individuals must be capable of meeting those demands to be considered as human resources.

2. Willing to work:
In addition to being able to work, a person also needs to be willing to work. This means having the motivation, dedication, and enthusiasm to perform the tasks assigned to them. Willingness to work implies a positive attitude towards the job and a commitment to fulfilling their responsibilities.

3. Belongs to a particular age group:
While the ability and willingness to work are crucial factors in becoming a human resource, age can also play a role in determining eligibility. Different organizations may have specific age requirements or preferences based on the nature of the job or legal regulations. For example, some jobs may require a minimum age limit due to safety concerns or legal restrictions.

Conclusion:
In summary, a person becomes a human resource when they possess the ability to work, are willing to work, and belong to a particular age group. These criteria ensure that individuals are suitable for employment within an organization and can contribute effectively to its operations and success.