1. According to the quantum mechanics, which is the correct statement for 3s, 3p and 3d of a helium ion, He⁺? (A) The orbital radii are the same for 3s, 3p and 3d. (B) 3s, 3p and 3d are degenerate. (C) The order of their energy levels is 3s ＜ 3p ＜ 3d. (D) 3s, 3p and 3d have the same number of the radial nodes. (E) The order of their energy levels is 3s ＞ 3p ＞ 3d.