If a sequence of data points, i.e., {a,b,c,d,e,f,g} has been pushed into a Stack following the given order, which of the following can be the output of pop? (select all that apply) Note: different output sequences can be generated because pop and push calls can be combined differently. E.g., push(a) and pop(), and then push(b), etc. {f,e,g,d,a,c,b} {c,d,b,e,f,a,g} {d,e,c,f,b,g,a} {e,f,d,g,b,c,a}