Final Answer:
Unsolicited email that plagues employees at all levels and clogs email systems is referred to as Spam (Option B).
Step-by-step explanation:
Spam (Option B) is unwanted and often irrelevant or inappropriate email sent to a large number of recipients, with the primary goal of advertising, phishing, or spreading malware. Spam emails can inundate email systems, causing disruptions, consuming bandwidth, and posing security risks. Unlike newsletters (Option A), memos (Option C), or announcements (Option D), which are typically authorized and expected communications within an organization, spam is characterized by its intrusive and disruptive nature. Effective email filters and security measures are commonly employed to mitigate the impact of spam and protect email users.
Option B is the answer.