A set of twins work in the Sears Tower, a very tall office building in Chicago. One works on the top floor and the other works in the basement. Considering general relativity, which twin will age more slowly? 

(a) They will age at the same rate. 

(b) The twin who works on the top floor will age more slowly. 

(c) The twin who works in the basement will age more slowly. 

(d) It depends on the building’s speed. 

(e) None of the previous choices is correct.