题目内容：
请在第__(49)__处填上正确答案。
A．Unfortunately, however, the plant started to become weaker and more prone to disease. B．Sugar cane is now much more vigorous and the supply of sugar is therefore more guaranteed.
C．One major gene has been identified by Dr. Angelique D'Hont and her team in Montpelier, France.
D．The majority of the world's sugar now comes from this particular commercial species.
E．Since the 1960s, scientists have been analysing the mysterious of the sugar canes genetic code.
F．Eventually, a commercial plant was developed which was 5 percent sweeter than before, but also much stronger and less likely to die from disease.
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