Final answer:
The ion that represents an element from Group 2A is D. A²⁺, because elements in Group 2A form 2+ charged cations.
Step-by-step explanation:
You asked which of the following ions would represent the ion of an element from Group 2A: A. X²⁻, B. Y³⁺, C. Z⁺, or D. A²⁺.
Elements in Group 2A of the periodic table are known as the alkaline earth metals. These elements typically lose two electrons to form cations with a 2+ charge. Therefore, the correct answer to your question is D. A²⁺, as this represents a 2+ charged ion, which is consistent with the expected ion charge for elements from Group 2A.