Multiple Single SNMP managers are communicating with a single SNMP agent in:.

many-to-many

Explanation:

Many-to-Many Communication is a term that describes a form of online or over the internet communication whereby numerous users are sending and receiving information, in such a way that the recipient does not have the idea of who the receiver is, and neither does the receiver know who the sender is, even though the information facets frequently connects through various websites.

Hence, Multiple Single SNMP managers are communicating with a single SNMP agent in "many-to-many communication."

it can either be 2. or 4. : ) tell me if i'm wrong or right

yes you can very simple, click the heart and then click the follow requests button.