The passage suggests which of the following about the recent research mentioned in the last sentence ? A. It has solved one set of problems but has created another. B. It has concentrated on secondary concerns but has ignored primary concerns. C. It has improved practical applications of biomaterial technology without providing a complete theoretical explanation of that improvement. D. It has thoroughly investigated properties of biomaterials but has paid little attention to relevant characteristics of human tissue. E. It has provided considerable information on short-term implant technology but little on long-term implant technology.