How does the server set cookies?

I am just reading a book and I have an excercise question. I am bit confused how does the server set cookies?

a. Browser automatically requests for cookies from a standarized URL b. Cookies are included in the head element of the html pages c. Cookies are given in HTTP headers d. Cookies are given using the link tag and loaded as separated files

I think the right answer is 'a' but I am not sure.