Please explain how the answer was obtained. thanks

Given the following data:

Units Produced: $10,000$

Direct Materials cost per unit: $$5$

Direct Labor cost per unit: $$4$

Variable Overhead Costs per unit: $$3$

Fixed Overhead costs per unit: $$6($will not change$)$

Purchase Price per unit if bought: $$15$

Additional rent revenue generated if the product is bought: $$35,000$

Should the company make or buy the product?

A$)$ Make the product because it will save $$30,000$

B$)$ Buy the product because it wil save $$30,000$

C$)$ Make the product because it will save $$5,000$

D$)$ Buy the product because it will save $$5,000$