to create, test, and improve products to manage the manufacturing of products to persuade customers to buy the products to label, package, and send products to retail stores
I gave my students this multiple choice question: Which of the following is the most important function of the research and development department of a large corporation?

Only one answer is correct among these 4 choices:
- to create, test, and improve products
- to manage the manufacturing of products
- to persuade customers to buy the products
- to label, package, and send products to retail stores

Could you tell me which one is correct?

to create, test, and improve products