Which abbreviation should be spelled out when first introduced in a text?

In academic writing, particularly in accordance with APA Style guidelines, it is essential to spell out any abbreviation the first time it is used in the text followed by the abbreviation in parentheses. This practice helps to ensure clarity for readers who may not be familiar with the abbreviated terms.

In this context, all three options—Electroconvulsive Therapy, Electroencephalogram, and Rapid Eye Movement—are proper abbreviations that require being fully spelled out on their first introduction. For instance, Electroconvulsive Therapy should be written out in full as the first reference in the text, followed by (ECT); similarly with the other terms. Therefore, the correct response indicating that none of these options should be left unspelled when first introduced—suggesting that the abbreviation must always be spelled out—is properly represented in the given answer.