A、Fishing and hunting. B、He began to show great interest in natural beauty. C、Nuclear science. D、Amateur radio. D信息明示题，文章第二段指出，.

At sixteen, Henry Vincent was separated from his family as a result of the war. He wandered aimlessly from one country to another before finally settling down in Australia, where he trained as an electronics engineer. He established his own business but it called for so much work that marriage was out of the question.
    His retirement suddenly made him realize how lonely he was and he decided to take up a hobby. With his interest in electronics, being an amateur radio operator seemed a natural choice. He installed his own equipment and obtained a license and his call sign, which is the set of letters and numbers used to identify oneself when making radio contact with other amateur operators all over the world.
    Soon Henry had a great many contacts in far off places. One in particular was a man in California with whom he had much in common. One night the man in California happened to mention the village in Europe he had come from. Suddenly, Henry realized that this man was in fact his younger brother, Peter. At first, the two brothers were at a loss for words but then little by little they filled in the details of their past lives and not long afterwards Henry Vincent flew to California to be reunited with his brother.