Which of the Following Conditions Is Not Required for an Employee

Which of the following conditions is not required for an employee stock purchase plan to be non-compensatory?

A) The plan is made available to substantially all employees.
B) After the plan is established, there is a maximum one-month period to elect to participate in the plan.
C) The discount is not larger than 5% of the open market price.
D) Top-level employees may purchase no more than a set percentage of shares available.