B - A chemist might determine the fat content in a candy bar.
1) Fatty acids stored in candy bars are (in fact) composed of chemical substances.
2) Choice A makes no sense. This activity belongs in the Biology field. Or if you're an animal activist, you might be interested in undertaking this as a hobby.
3) Choice C is absurd because either you're a Physicist who enjoys an occupation such as this, or you're just plain crazy.
4) Choice D is preposterous because either you're a Meteorologist, or a Geoscientist. Both of which have nothing to do with chemistry.