"A child is dying---out of breath!" I had just begun my working day in the city, when these words came through the radio of the police car I was driving. I turned on the red lights and siren and drove off as fast as I could. "Just my luck!" I thought. I didn't know this city well and my first call of the day was a life-and-death sudden happening, several kilometers away. I got to the house. A mother, filled with fear, handed me her baby, his face already blue. Was I too late? Dear me! I did what had been taught to do in such a serious condition. A small thing flew out of the baby's mouth on to the floor. It was a button. Thank heaven! The holes in it let a little air through. A doctor rushed into the room. He had with him an oxygen bag. The child began to cry at the top of his voice, burned red and started to look for his mother. He was angry but was saved. The baby was still living when the writer got to the house because   _  .
the writer arrived in time the writer had been taught what to do at that time the button was not big enough the button happened to have holes in it