You and three of your friends run a car wash for a fund-raiser. Between interior and exterior cleaning, you spend about 40 minutes per vehicle. You are so successful that the next day you invite four more friends to help. How does this impact the labor content? 

a. The labor content goes up. 

b. The labor content stays the same. 

c. The labor content goes down. 

d. Cannot determine from the given information.