If you are asking what is a stanza, then it is <em>the line structure of the poem.</em> Stanzas can be long or short in a poem. Poems are usually structured and divided in stanzas.
 
        
             
        
        
        
The events that took place or for short, "the events" is the direct object of your sentence. 
        
                    
             
        
        
        
The correct answer is Queen Gertrude is caught between her new husband and her son. 
B is definitely incorrect because his father is dead so he cannot observe his conversation; C is incorrect because Gertrude believes Hamlet should blindly follow what Claudius has to say; D is incorrect because Hamlet hates Claudius.
This leaves us with sentence A - Gertrude has just lost her husband but she remarried immediately. Now, she is torn between her son whom she loves, and her new husband, who she feels she should obey.