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​

The punctuation in line 8 Where they have been grazing all day alone serves mainly to Select one Oextend the range of the poets observations O suggest the horse class=