A sales executive's monthly salary has two components: a percentage commission on the achieved sales and a fixed amount. For the first 3 years, the percentage commissions were 30%, 20%, and 10% respectively and his fixed salary was 1000, 2000 and 3000. It was seen that the total yearly salary he received for the first 3 years was exactly thesame for each year. Now, what can be said about his annual sales?

a. His annual sales+has been growing.
b. His annual sales has been falling.
c. His annual sales cannot have gone up in the second ear and then gone down in the third.
d. His annual sales went up in the second year and again come down in the third year.