Karate class is trying to raise money for a trip to the national championship. They are selling "Toe Socks" as a their fundraiser. The graph below shows their sales for the last three months.

Which statement is true?

a.) The most earned in any month was $400.

b.) The class earned twice as much in week 2 as in week 1.

c.) The mean earnings for 3 weeks was $400 per week.

d.) The class earned a total of $1,400 in the three week period.