Read the extract given below and answer the questions that follow: O what is that sound which so thrills the ear Down in the valley drumming, drumming? Only the scarlet soldiers, dear, The soldiers coming. O what is that light I see flashing so clear Over the distance brightly, brightly? Only the sun on their weapons, dear, As they step lightly. O what are they doing with all that gear, What are they doing this morning, this morning? Only the usual manoeuvres, dear, Or perhaps a warning. O why have they left the road down there, Why are they suddenly wheeling, wheeling? Perhaps a change in the orders, dear, Why are you kneeling? Identify the rhyme scheme of these lines.