Answer:
D) 4f
Explanation:
To determine which electron orbital that will have higher energy than a 4d orbital, we write the electron configuration starting with s-orbital.
1s 
2s         2p
3s         3p          3d       3f
4s         4p          4d       4f
5s         5p           5d       5f
6s         6p          6d       6f
7s         7p           7d       7f
In ascending order, 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 3f, <u>4d</u><em>,</em> 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p, 6f, 7d, 7f.
From the electronic configuration formula above, the electron orbitals that have higher energy than a 4d orbital are 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p, 6f, 7d, 7f.
Therefore, 4f is the correct answer.