Suppose Spencer and Kate are the only two demanders of lemonade. Each month, Spencer buys six glasses of lemonade when the price is $1.00 per glass, and he buys four glasses when the price is $1.50 per glass. Each month, Kate buys four glasses of lemonade when the price is $1.00 per glass, and she buys two glasses when the price is $1.50 per glass. Which of the following points is on the market demand curve?
a. (quantity demanded = 3, price = $1.50)
b. (quantity demanded = 4, price = $2.50)
c. (quantity demanded = 10, price = $1.00)
d. (quantity demanded = 16, price = $2.50)