Mandy has an income of $800 in period 1 and will have an income of $500 in period 2. Her utility function is Cobb-Douglas, given by U(c1, c2) = 0.80c1^1.20c2^0.20. What is Mandy's utility function?
a) U(c1, c2) = 0.80c1^1.20c2^0.20
b) U(c1, c2) = 0.20c1^0.80c2^1.20
c) U(c1, c2) = 1.20c1^0.80c2^0.20
d) U(c1, c2) = 0.20c1^1.20c2^0.80