Final answer:
A command-referral can be initiated based on personal observation, hearsay, or noticeable change in job performance.
Step-by-step explanation:
A command-referral is initiated by the member's chain of command and may be based on a credible factor such as: a) personal observation, b) hearsay, c) noticeable change in job performance, d) all of these.
Credible information refers to information that is reliable, accurate, and trustworthy. In the given options, all of these factors can be considered credible as they have the potential to provide reliable information. Personal observation allows for firsthand knowledge, hearsay can be based on reliable sources, and noticeable changes in job performance can indicate a problem. Therefore, the correct answer is d) all of these.