Final answer:
Among the given species, AlCl4 is the one that possesses a formal charge due to an excess of electrons around aluminum, leading to a -1 charge on the complex. The option (C) is correct.
Step-by-step explanation:
The species that possesses a formal charge among the options given is AlCl4. This is because aluminum in AlCl4 typically has a +3 oxidation state, but in the given species, it forms four covalent bonds with chlorine atoms. This leads to an excess of electrons around aluminum, which results in a formal charge of -1 on the AlCl4 complex.
The other compounds, CCl4, SiCl4, and PCl3 have no formal charges because the central atoms follow the octet rule without any excess or deficiency of electrons. Therefore, option (C) is correct.