Which of the Following Statements Is TRUE

Which of the following statements is TRUE?

A) An orbital that penetrates into the region occupied by core electrons is less shielded from nuclear charge than an orbital that does not penetrate and therefore has a lower energy.
B) An orbital that penetrates into the region occupied by core electrons is more shielded from nuclear charge than an orbital that does not penetrate and therefore has a lower energy.
C) It is possible for two electrons in the same atom to have identical values for all four quantum numbers.
D) Two electrons in the same orbital can have the same spin.
E) None of the above are true.