There is no hope of ____________________ (艾滋病患者从这种不治之症中痊愈).

A．It is questionable whether American economy can produce enough assets.
B．If pensions are owned by private sector, baby-boomers don’t need to worry.
C．The pyramid-scheme pattern of asset markets is undeniablly fixed.
D．Savers can always sell assets at higher prices.

According to John Maynard Keynes, why can governments use devaluation of currency to take in people