The punctuation in line 8 ("Where they have been grazing all day, alone") serves mainly to Select one: 
Oextend the range of the poet's observations 
O suggest the horses' need for attention 
Oconvey the poet's intensity 
O divulge the horses' specific activities 
O interrupt the description of the horses​
                                             
                                          
                                          
                                        
											 
			                  