The program needs to be written in C.

the program can only accept 4 letters.

must exit if there is nothing in the command line.

the print out does not need to be side by side.

4. Write recursive functions that list all of the one-element, twO-el three-element subsets of a given set of letters. For example em ent, one ele subs ("ACEG") fA) fcy E) two ele subs ("ACEG") (, } A, Eh A, G (C, EH (C, G IE, GH three_ele_subs ("ACEG") A, C, E) A, C, G) A, E, G) (C, E, G)