If you want this painkiller, you'll have to ask the doctor for a （）

A．make clear the complex chemistry in the development of life
B．confirm the suggestion that bacterial fossils traveled to Earth on a meteorite
C．reveal the kind of conditions under which life originates
D．provide an explanation why life is common in the universe

A．with Mars the risks involved are much greater than any previous space ventures
B．in the case of Mars, the rewards of scientific exploration can be very high
C．in the case of Mars, much more research funds are needed than ever before
D．with Mars scientists argue, the fundamental interests of science are at issue