3s3p4s3d
3s3p3d4s
3s4s3p3d
4s3s3p3d
The correct order of increasing energy of the listed orbitals in the atom of titanium is 3s < 3p < 4s < 3d. The energy of the 4s orbital is lower than the energy of the 3d orbital. Due to this, the 4s orbital is filled first, followed by the 3d orbital.