Please help! I have 2 remaining attempts and only 2 of my answers are incorrect. Please let me know which reactions are wrong and where they should be put! LOTS OF POINTS

An engineer decides to use a slightly weaker material rather than a stronger material, since she knows that the stronger material can break suddenly. this is an example of what? a choosing a material that will show warning before it fails b using composite materials that combine strength c using a material for multiple applications d using design techniques that increase efficiency and reduce cost