The XYZ Company manufactures two types of lawnmowers. Type A is propelled, and type B must be pushed by the operator. The company can produce a maximum of 18 mowers per week. It can make a profit of $20 on mower A and a profit of $25 on mower B. The company's planners want to make at least 2 mowers of each type A but not more than 5. To keep certain customers happy, they must make at least 2 mowers of type B. What are the constraints? 

I. x+y≤18

 II. x≥2 

III. y≥2

 IV. x≥5

a. I only

b. II only

c, I,II and III only

d. I, II, III, and IV

*what is the letter of the correct answer?