Q. Which of the following statement is correct as regard to the difference between a machine and a structure?

• (A) The parts of a machine move relative to one another, whereas the members of a structure do not move relative to one another
• (B) The links of a machine may transmit both power and motion, whereas the members of a structure transmit forces only
• (C) A machine transforms the available energy into some useful work, whereas in a structure no energy is transformed into useful work
• (D) All of the above