All of the following affect metabolism except:
a. age
b. gender
c. genetic differences
d. the temperature outside

None of the above. All of the following affect metabolism at some point in an individual's life. As a person ages, metabolic rate generally slows down because of muscle tissue loss, and some hormonal and neurological changes. Gender also affects metabolism because men are generally larger in size than women that is why they tend to have faster metabolisms than women. Genes or inherited traits from parents also affect metabolism, the rate at which the body goes is dependent on inherited traits from parents, also the diseases that come with abnormal genes can affect metabolism. Temperature can also affect metabolism because the body adjusts to maintain its normal temperature which can either increase or decrease metabolic rate.

In fact it is not just nuclear fusion and fission that  can  transform  matter  (or mass)into energy. any time  energy  is produced, some small amount of  matter  or mass isconverted into energy.