how to understand it ? understand, investment, following, increase

sinowonder

which of the following are the most likely effects of an increase in tax on interest income on the investment demand and interest rates,respectively?

effect on investment demand,effect on interest rates

a.no effect,no effect

b.no effect,increase

c.decrease,no effect

answer is b.

how to understand it ?

minminmin

可以讲一下这个题目的出处么？