Final answer:
The electron configuration of the calcium ion (Ca^2+) is 1s^22s^22p^63s^23p^6, which corresponds to the configuration of Argon (Ar), a noble gas.
Step-by-step explanation:
The electron configuration of a calcium ion (Ca2+) can be derived from the electron configuration of a neutral calcium atom. Calcium's ground state electron configuration is [Ar]4s2. When calcium forms a Ca2+ ion, it loses two electrons, both of which come from the 4s sublevel, resulting in a new electron configuration which matches that of Argon (Ar), a noble gas.
Thus, the electron configuration of the calcium ion (Ca2+) is 1s22s22p63s23p6. This corresponds to option 2 in the provided choices.