Final answer:
APA style requires the use of a block quotation when the quote exceeds forty words, formatted with an indentation of one-half inch and does not include quotation marks.
Step-by-step explanation:
The correct answer to when an APA style requires the use of a block quotation is when a quote is longer than forty words. According to APA guidelines, quotes that exceed this length should be formatted as a block quote. The block quote is distinctively formatted by indenting the entire quote one-half inch from the left margin and is double spaced, without quotation marks. The ending punctuation of the quote is placed before the parenthetical citation. This method highlights the quote visually, setting it apart from the rest of the text, and signals to the reader that the subsequent material is a direct quote from a source.