Andi, the $100$ percent owner of Andi's Landscape Design, would like to establish a profit sharing plan. Andi's fiscal year ends December $31.$ What is the latest day Andi can establish and contribute to the plan?

a$.)$Andi must establish and contribute to the plan by December $31$ of the year in which she would like to establish the plan.

b$.)$Andi must establish the plan and make contributions by the due date of the company's tax return $($including extensions$)$ for the tax year for which the employer wants to mae contributions $.$

c$.)$ Andi must establish the plan by July $31$ of the year in which she would like to establish the plan an d contribute by December $31.$

d$.)$ Andi must establish the plan by December $31$ of the year in which she would like to establish the plan and contribute to the plan by April $15$ of the following year.