Which of the below listed items does not match the National Labor Relations Act definition of a "professional employee."

Question $6$ options:

$1)$

Involves the consisent exercise of discretion and judgement.

$2)$

Requires knowledge of an advanced type of learning customarily acquired by a prolonged course of instruction.

$3)$

Performs predominantly intellectual work.

$4)$

Is often a union eligible employee.