Answer:
The coordination sphere of a complex consists of <u><em>the central metal ion and the ligands bonded to it.</em></u>
Explanation:
The Coordination Compounds are sets of a central metal ion attached to a group of molecules or ions that surround it. They are also called metal complexes or simply complexes. Then they are compounds that have a central atom surrounded by a group of molecules or ions, the latter called ligands.
The central atom must have empty orbitals capable of accepting pairs of electrons, with the transition metals being the ones with the greatest tendency. Because of this, they can act as Lewis acids (electron pair acceptors). The ligands have unshared electron pairs, then acting as Lewis bases (electron pair donors).
When forming a complex, it is said that the ligands coordinate to the metal and the central metal and the ligands attached to it constitute the coordination sphere of the complex.
Finally, <u><em>the coordination sphere of a complex consists of the central metal ion and the ligands bonded to it.</em></u>
Leah's experiment:
A. Takes careful and regular measurements (she measures the growth every day)
B. Has a specific hypothesis and a controlled experiment (the music is the only changing variable, the growth conditions are identical, and this is what she wants to test in her hypothesis)
C. Experimental data that can be recorded and analyzed (measuring the growth of plant fits this)
So the answer must be D, since there is no mention of past research that scientists have found on this topic.