Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 36 to 42.

    When we moved to our new house near the sea, I was eight years old. Even before that I had spent every summer messing about on boats. My dad had taught me to sail before I learnt to ride a bike so I knew how I wanted to spend my time at the new house- I was going to get my own boat and sail it everyday. The house was only a few meters from the water's edge, and in rough weather the waves would come crashing into the front garden. I used to sit with my nose pressed to the glass, fascinated by the power of the ocean. I grew up watching the skies to see if it was going to rain; would I be going sailing that afternoon or not?

          Of course I sometimes wished I could live in the town like my friends. I used to get irritated with my parents, who had taken early retirement because they seemed incapable of getting anywhere on time. Dad drove me the eight miles to school everyday, but I was often late because he had been walking on the cliffs earlier in the morning and had lost track of time. When I was taking my university entrance exams, I used to stay over at a friend’s in town, just in case. All in all, I was lucky to grow up by the sea and I still love to sail

The writer's father retired early because ___________.