begins the first study under subsection (b), the headings or subheadings of the Harmonized Tariff Schedule of the United States are changed, or any products are added to or removed from a heading or subheading, the Secretary may continue, in that or any subsequent study, to study the applicable products as if the applicable change had not occurred. (5) Covered country The term covered country means each of the following: (A) A country that is a member of the Group of Seven. (B) A country that is a signatory to a free trade agreement with the United States that is in effect as of the date on which the Secretary begins a study under subsection (b)(1). (C) A foreign country of concern (as defined in section 9901 of the William M. (Mac) Thornberry National Defense Authorization Act for Fiscal Year 2021 ( 15 U.S.C. 4651 )). (D) A country that, in the determination of the Secretary, holds more than a de minimis share of the global market share, as measured by official trade statistics, of— (i) 1 or more categories of covered products