题目内容：
请在第__(50)__处填上正确答案。
A．Eventually, a commercial plant was developed which was 5 percent sweeter than before, but also much stronger and less likely to die from disease. B．One major gene has been identified by Dr. Angelique D'Hont and her team in Montpelier, France.
C．Sugar cane is now much more vigorous and the supply of sugar is therefore more guaranteed.
D．Since the 1960s, scientists have been analyzing the mysteries of the sugar cane's genetic code.
E．The majority of the world's sugar now comes from this particular commercial species.
F．Unfortunately, however, the plant started to become weaker and more prone to disease.
参考答案：
答案解析：