The molecules that make up food contain energy. how does the human body get energy from the food molecules?
a- by breaking and reforming chemical bonds in the molecules
b- by combining the molecules together
c- by using them to from ionic bonds
d- by adding energy to the molecules

 A: by breaking ans reforming chemical bonds in the molecules

Explanation: There is energy stored in chemical bonds between food molecules (this is referred to as ATP, or Adenosine TriPhosphate, which is the type of energy your body uses).  When chemical bonds are created, some energy is stored in those bonds (personally, I like to think that it's because the bonds need energy to stay bonded, but there is no science to prove this).  When one of these bonds are broken, the energy that was stored is released, and can then be used by your body.  Your body then uses a different type of energy (called ADP, or Adenosine DiPhosphate) to reform the bonds, which then go on to become waste products.