B、The popularity of the American candy bar industry.
C、The candy bar industry during World War I.
D、The spread of the candy bar business to the Midwest.
Directions:In each of the following groups of words,there are four underlined letters or letter combinations marked A,B,C and D.Compare the underlined parts and iden-tdtify the one that is different from the others in pronunciation.Mark your answer by blackening the corresponding letter on the Answer Sheet.
A、combination
B、climbing
C、bamboo
D、ambition
49.Which event brought the booming of American candy bar business?