Q:I'm taking a test and have to guess the right answer to the question after the article. Article: Linus Pauling, the only person who has won two undivided Nobel Prizes, was born in Portland, Oregon. He attended Washington High School but because of an unimportant detail he did not receive his diploma until 1962, long after he had received his Bachelor's degree in chemical engineering from Oregon State College in 1922. He had chosen to study this major because he could get a good job with it. He won the Nobel Prize for Chemistry in 1954 "for his research into the nature of the chemical bond and its application to the explanation of the structure of complex substances". His interest in the "behavior" of molecules led him from physical chemistry to biological chemistry, especially of the human body. He began with proteins and their main parts, the amino acids , which are called the "building blocks of life". In 1950, he constructed the first satisfactory model of a protein molecule, a discovery very important to the understanding of the living cell. During World War II, Pauling was a member of the Research Board for National Security, for which he was awarded the Presidential Medal of Merit in 1948. However, the use of the atomic bomb near the end of the war turned Pauling in a new direction. Having long worked on the structure of molecules, he took an immediate interest in the deadly effects of nuclear fallout on human molecular structures. From then on, Pauling protested the production of the hydrogen bomb and supported the prevention of the spread of nuclear weapons. Through his efforts, The Nuclear-Test-Ban Treaty, declaring all nuclear tests to be illegal except underground ones, came into effect on October 10, 1963, the same day Linus Pauling was awarded the Nobel Prize for Peace. Question: Which of the following things did Pauling pay much attention to at first? Options: A: The "behavior" of molecules. B: Physical chemistry. C: Biological chemistry. D: The human body.
A:
B