Step 1: Understanding recruitment in an organization. 
  
Recruitment is an ongoing process in most organizations. As organizations grow and evolve, they continuously hire employees to meet changing needs, expand their workforce, and replace retiring or leaving staff. Recruitment happens regularly and continuously. 
Step 2: Analyzing the options. 
  
(A) Once: Incorrect. Recruitment is not a one-time activity. 
  
(B) Twice: Incorrect. Recruitment is not limited to a specific number of times; it is an ongoing process. 
  
(C) Occasionally: Incorrect. While recruitment may happen periodically, it is not occasional but continuous in nature. 
  
(D) Continuous: Correct. Recruitment is an ongoing and continuous process in any organization. 
Step 3: Conclusion. 
  
The correct answer is (D) Continuous, as recruitment is a constant and ongoing process for organizations.