What is the difference between the electron shells, the subshells, and the orbitals?

Electron shells are the discrete energy level in an atom where we can find electrons, it is same as electron orbit.If we further divides energy level of a electron shells then it is called Electron subshell, it is same as electron orbitals, furthermore the classical figure shown in textbooks for s,p,d,f are actually the area where the probability of finding an electron is maximum

The answer is b on plato.