Answer: D. the National Labor Relations Board
Explanation:
The National Labor Relations Board as empowered by the National Labor Relations Act of 1935 has the responsibility to hold elections where workers will decide if they want to join a union or rather be represented by one.
For a Union to approach the Board for an election, it need to show sufficient evidence of support for such an election from the workers they wish to represent which is why the Auto Workers Union (AUW) had to gather enough employee signatures.