Suppose we have the following Postfix notation "x z* r/m f/b*+ i +a t*-" and we are creating the expression tree. If the current step is to read operator "*" after reading "b". Which graphic (representing the state of the stack) illustrates the current step? 0 Figure 1 2 Figure 2 Figure 3 Select one: O a. Figure 3 O b. Figure 1 O c. Figure 2