To find percent composition, you should first find the total of all of the components. Just add them all together:
[tex]100g+200g+50g=350g[/tex]
Then, divide the amount of the component you are interested in, in this case, chocolate (50g), by the total amount to give:
[tex] \frac{50g}{350g} [/tex]
This will give you the answer in decimal form, but to convert to a percent, you need to multiply by 100:
[tex] \frac{50g}{350g}*100 [/tex]
Therefore, the answer choice that is correct is A.
