题目

阅读理解From the top of Mount Qomolangma to the bottom of the MarianaTrench, plastic continues to pollute the environment, and it creates a significantthreat to all life forms on Earth. Despite knowing the effects of plastic pollution,we have not been able to ban the use of plastic products. Now, thanks to the inventionof a 17-year-old girl, Arora, we finally have a better choice. This plastic-likematerial is made from prawn (大虾) shells, and it breaks down 1.5 million times faster than most of thecommercial plastic products we use today.The Australian teen first became aware of the imp在有理数范围内定义运算“”，其规则为ab=，则方程（23）（4x）=49的解为（     ） A．-3      B．55     C．-56     D．-55