An analyst does research about consumer surplus and producer surplus. When monopolies can use perfectly price discrimination, consumer surplus is:（）

单项选择题An investor does research about net present value and gathers the information about two trust products with the same positive annual payments to investor. One is a 20-year ordinary annuity, and the other is a 10-year ordinary annuity. If the investor uses the same positive discount rate to analyze both products, the present value of the lO-year ordinary annuity is:（）

A. less than half the present value of the 20-year ordinary annuity.
B. equal to half the present value of the 20-year ordinary annuity.
C. greater than half the present value of the 20-year ordinary annuity.

单项选择题With respect to a candlestick chart, the body of the candle is clear if the opening price was:（）

A. less than the closing price.
B. equal to the closing price.
C. greater than the closing price.