Final answer:
In MLA 8 format, the end punctuation for a quoted sentence, when accompanied by a signal phrase, should be placed before the closing quotation mark.
Step-by-step explanation:
When using MLA 8 format for quotations, proper punctuation is essential to ensure clarity and to attribute the source correctly. If your citation has already appeared in your sentence, such as with a signal phrase, the correct placement of the end punctuation in a quoted sentence is before the closing quotation mark. To illustrate this, consider the sentence: As Martin writes, "Bears will attack you if you do not give them all of your money." The period should be placed after the word 'money' and before the closing quotation mark.
It's important to note that periods and commas typically go inside the quotation marks in MLA style. In contrast, colons and semicolons go outside the quotation marks. When quotations are used, signal phrases like "Martin writes" should be followed by a comma, separating it from the quoted material that is enclosed within double quotation marks.