C, because if you are using music to relax, you want music that is peaceful, and that it wont cause singing. The purpose of relaxing is to be in peace and tranquility. dozing off is okay because it signifies that the body is tired and needs to be deeply relaxed.
Individual decision making is more limited than collaborative decision making because as an individual you would only have one or two points of view on the subject as well as knowledge and ideas. If you were to work with more people to decide on something then there would be a good chance that everyone would be able to pitch in ideas and different points of views to overall decide.
What isn't a function of proteins is storage and the transmission of heredity - a. For this job we have DNA and not proteins. For all the other things you've listed - help in fighting disease, control over the rate of reactions and regulation of cell processes and bone and muscle formations all are example of what proteins do.
C. deck of cards is your answer
