D. All of the above.
In the career world, it is best to never “burn bridges,” so to speak. In fact, you’ll want to maintain and nurture all professional relationships you have and foster a professional network. This will benefit you if you are ever fired or laid off and need to return to an old job or ask previous colleagues and managers to be listed as references or for a letter of reference. Additionally, you can always provide assistance to those seeking your help/advice one day should a past colleague need it. Lastly, by maintaining a network of relationships, you’ll always be kept abreast of current happenings which could benefit you as your knowledge in your career field will be reliable and valid and be kept safe from becoming antiquated/irrelevant.