Final answer:
Johann could receive spam during an IM session if his IM account is compromised. He should change his password and enable two-factor authentication to secure his account.
Step-by-step explanation:
The statement that would explain why Johann could receive spam during an IM session is b) Johann's IM account is compromised. When an IM account is compromised, it means that someone has unauthorized access to it and can send spam messages to the account holder and their contacts. This can happen if Johann's account information has been obtained by spammers, possibly through phishing attacks, malware, or if he has used the same password on multiple sites that have had a security breach. It is important to note that IM platforms, like many other communication channels, are not inherently secure and can be susceptible to spam and other security threats. It is important for Johann to change his password immediately and enable two-factor authentication to secure his IM account.