Which numbers are necessary to solve this problem? 
 A fence company has been in business for 18 months. It makes 450 white posts and 200 beige posts a day. 
 How many posts will the company make in 4 days?
 A.
 450 white posts, 200 beige posts
 B.
 450 white posts, 200 beige posts, 4 days
 C.
 18 months, 450 white posts, 200 beige posts
 D.
 18 months, 450 white posts, 200 beige posts, 4 days