Trace a stack (called S) through the following operations: Stack S = new Stack( ) ; S . push (new I n t e g e r ( 7 ) ) ; I n t e g e r X = S . pop ( ) ; S . push (new I n t e g e r ( 4 ) ) ; S . push (new I n t e g e r ( 5 ) ) ; I n t e g e r Y = S . peek ( ) ; S . push (new I n t e g e r ( 1 ) ) ; S . push (new I n t e g e r ( 3 ) ) ; I n t e g e r Z = S . pop ( ) ; Y = S . pop ( ) ; Give the contents of the stack after this code has been executed. (a) 4 5 (top) (b) 4 (top) (c) 7 4 1 3 (top) (d) None of the above.