What follows is an opinion from a United States Court of Appeals. Your task is to identify the federal agency (if any) whose decision was reviewed by the court of appeals. If there was no prior agency action, choose "not applicable".

Opinion:
FOSTER TRANSFORMER COMPANY, Petitioner, v. NATIONAL LABOR RELATIONS BOARD, Respondent.
No. 73-1853.
United States Court of Appeals, Sixth Circuit.
Argued Feb. 4, 1974.
Decided Feb. 15, 1974.
J. Mack Swigert, Thorley C. Mills, Jr., Cincinnati, Ohio, on brief, for petitioner.
Peter G. Nash, Gen. Counsel, John S. Irving, Deputy Gen. Counsel, Patrick Hardin, Associate Gen. Counsel, Elliott Moore, Deputy Associate Gen. Counsel, Robert Sewell, John Ferguson, Warren Ogden, Attys., National Labor Relations Board, Washington, D. C., on brief, for respondent.
Before PHILLIPS, Chief Judge, McCREE, Circuit Judge, and ROSENSTEIN, Senior Customs Judge.
Senior Judge Samuel M. Rosenstein, United States Customs Court, sitting by designation.
ORDER
This case is before the court on the petition of Foster Transformer Company to review a decision of the National Labor Relations Board, and the cross-application of the Board for enforcement of its order. Reference is made to the decision of the Board, reported at 205 N.L.R.B. 82, for a recitation of pertinent facts.
The court is of the view that the Board properly concluded that the company violated § 8(a)(5) and (1) of the Act by refusing to bargain with the certified representative of its employees, and that the Board did not abuse its discretion in overruling the objections of the Company to the election.
It is ordered that the order of the Board be enforced.
Entered by order of the court.

Question: What federal agency's decision was reviewed by the court of appeals?

Choices:
Benefits Review Board
Civil Aeronautics Board
Civil Service Commission
Federal Communications Commission
Federal Energy Regulatory Commission
Federal Power Commission
Federal Maritime Commission
Federal Trade Commission
Interstate Commerce Commission
National Labor Relations Board
Atomic Energy Commission
Nuclear Regulatory Commission
Securities & Exchange Commission
Other federal agency
Not ascertained or not applicable

Answer: 9