Identify arrows pointing to bonding electrons. An upper H is single bonded to an upper C, which is bonded to an upper O with pairs of dots above an below, which is bonded to an upper H. The upper C is double bonded above to an upper O, which has pairs of dots to the right and left. Arrow A points to the double bond, arrow B to the single bond between H and C, Arrow C to the dots below the O, and arrow D to the bond between O and H.