Step 1: Staffing Process Breakdown.
- (D): Personnel Requirement Determination. Ascertain the number of staff needed for open roles before initiating recruitment.
- (A): Candidate Sourcing and Engagement. Following needs assessment, identify and encourage suitable individuals to apply.
- (B): Offer Extension. Upon candidate selection, extend an offer letter to formalize the hiring.
- (C): Company Introduction. Provide a concise overview of the organization to selected applicants.
Step 2: Sequence Determination.
The logical order is:
(D), (A), (B), (C).
Final Answer: \[\boxed{\text{The correct answer is (3) (D), (A), (B), (C).}}\]