单选题 Which concept of the materials cycle has been LEAST AFFECTED by recent trends?
   A) Concern for the entire cycle that includes effects of harmful by-products and unrecycled old products
   B) Ability to design materials to meet ever-increasing demands of technology rather than use "off-the shelf" materials
   C) Need for a more highly educated workforce to support new manufacturing techniques
   D) Desire to achieve the maximum properties from any given materials