Find the best correction for the underlined sentence from the four options give below:
Under a provision of the Constitution that was never applied, Congress has been required to call a convention for considering possible amendments to the document when formally asked to do it by the legislatures of two-thirds of the states.
Option D is the right answer.
Options A and B contain tense errors (was never applied … has been required).
Option C is incorrect because of the use of “has” and “whereby” in incorrect tenses (has never applied, whereby Congress is required to call...).